What will be the next word of the series? ZAS, YBR, XCQ, ........

Question: What will be the next word of the series?
ZAS, YBR, XCQ, ........

Solution:
ZAS, YBR, XCQ,
from the series
the first letter of each word is in the opposite direction of X, Y, and Z. So, the letter before X is W

next letter is in the sequence of A, B, C. so the next letter will be D
third letter of the series is also in the opposite direction Q, R, and S . So, the letter before Q is P