Z - 5 = U - 4 = Q - 3 = N - 2 = L

A + 8 = I + 7 = P + 6 = V + 5 = A + 4 = E + 3 = H

The correct pattern is x 6 - 6, x 5 - 5, x 4 - 4,.....
So, 24 is wrong and must be replaced by (6 x 5 - 5) i.e. 25.

The given sequence is a combination of two series:
I. 45, 47, 49, 51, 53 and II. 54, ?, 56, 57
Clearly, II consists of consecutive natural numbers, starting from 54.
So, missing term = 55.

The given series may be divided into 2 series:
I: A, B, C, D, E, F, ?, ? and
II: N, O, P, ?
Clearly , the given series consists of two terms of followed by one term of II.
The missing terms in I are G and H while the missing term in II is Q.

There is a gap of four letters between the first and second, the second and third letters of each term, and also between the last letter of a term and the first letter of the next term.

A + 6 = G + 5 = L + 4 = P + 3 = S + 2 = U

1st letter : D + 12 = P + 12 = B + 12 = N
2nd letter : H + 12 = T + 12 = F + 12 = R
3rd letter : L + 12 = X + 12 = J + 12 = V

One letter from the beginning and one from the end of a term are removed, one by one, in alternate setps,

The given sequence is a combination of two series:
I: Y, T, O and
II: B, G, ?
I: consists of 2nd, 7th and 12th letters from the end of the English alphabet, while II: consists of 2nd, 7th and 12th letters from the beginning of the English alphabet.
So, the missing letter in is the 12th letter from the beginning of the English alphabet, which is L.

The given sequence is a combination of two series:
I: Z, W, T, Q, ? and
II: S, O, K, G,, ?
The pattern in I is: Z - 3 = W - 3 = T - 3 = Q - 3 = N
The pattern in II is : S - 4 = O - 4 = K - 4 = G - 4 = C

Each term consists of consecutive letters in order. The number of letters in the terms goes on increasing by one at each steps. Also, there is a gap of one letter between the last letter of the first term and the first letter of the second term; a gap of two letters between the last letter of the second term and the first letter of the third term; and so on. So, there should be a gap of three letters between the last letter of the third term and the first letter of the desired term.

1st letter : D + 3 = G + 4 = K + 3 = N + 4 = R + 3 = U
2nd letter : F + 4 = J + 3 = M + 4 = Q + 3 = T + 4 = X

1st letter : A + 1 = B + 1 = C + 1 = D + 1 = E
2nd letter : Z - 5 = U + (5 - 2) = + 3 = X - (3 - 2) = - 1 = W + (1 - 2) = - 1 = V
3rd letter : Y - 5 = T + (5 - 2) = + 3 = W - (3 - 2) = - 1 = V + (1 - 2) = - 1 = U

T - 2 = R - 2 = P - 2 = N - 2 = L - 2 = J - 2 = H

(Z→Y→X) - 3 (U→T→S) - 3 (P→O→N) - 3 (K→J→I)

Z - 2 = X - 5 = S - 10 = I - 17 = R - 26 = R - 37 = G - 50 = I

1st letter : A + 3 = D + 4 = H + 5 = M + 6 = S + 7 = Z
2nd letter : B + 5 = G + 6 = M + 7 = T + 8 = B + 9 = K
3rd letter : D + 7 = K + 8 = S + 9 = B + 10 = L + 11 = W

Each term of the series is obtained by removing two letters from the preceding term- one from the beginning and one from the end. So, the missing term is PENDICU.

The given sequence is a combination of two series:
I: C, F, I, L, O and
II: Z, X, V, T, ?
The pattern in I is :C + 3 F + 3 I + 3 L + 3 O + 3 R
The pattern in II is: Z - 2 X - 2 V - 2 T - 2 R

The given sequence is a combination of two series:
I: 1st , 3rd, 5th, 7th, 9th, 11th terms i.e., A, B, C, D, E, ?
II: 2nd, 4th, 6th, 8th, 10th terms i.e., B, D, F, H, ?
Clearly , I: consists of consecutive letters while II: consists of alternate letters.
So, the missing letter in I is F, while that in II is J.
So, the missing terms i.e., 10th and 11th terms re J and F respectively.

1st letter : a + 6 = g + 6 = m + 6 = s + 6 = y
2nd letter : j + 6 = p + 6 = v + 6 = b + 6 = h
3rd letter : s + 6 = y + 6 = e + 6 = k + 6 = q

1st letter : W - 3 = T - 3 = Q - 3 = N
2nd letter : F + 1 = G + 1 = H + 1 = I
3rd letter : B + 2 = D + 3 = G + 4 = K

The series may be divided into groups as shown:
b e d / f ? h / j ? l
Clearly in the first group, the second group and third group , letters are respectively three and two steps ahead of the first letter. A similar pattern would follow in the second and third groups.

H + 1 = I + 2 = K + 3 = N + 4 = R

U + 7 B + 7 I + 7 P + 7 W + 7 D

1st letter : U - 2 = S - 4 = O - 2 = M - 4 = I
2nd letter : P - 8 = H - 4 = D - 2 = B - 1 = A
3rd letter : I + 1 = J + 6 = P + 1 = Q + 6 = W