Correct option is D
Given:
8 # 2 @ 5 = 21
4 # 6 @ 2 = 26
Solution:if we suppose signs as # = ×, @ = +, then we get
8 # 2 @ 5 = 26
= 8 × 2 + 5
= 21 as given and another
4 # 6 @ 2 = 26
= 4× 6 + 2
= 26 (hence logic is correct)
Similarly, by applying the logic
3 # 7 @ 9
= 3 × 7 + 9
= 30
answer is option d