If 45% of (A - B) is equal to 3/10 of (A + B), then what percent of A is B?

Question: If 45% of (A - B) is equal to 3/10 of (A + B), then what percent of A is B?

Solution:
Given that,
45% of (A - B) = (3/10) of (A + B)
⇒ (45/100) of (A - B) = (3/10) of (A + B)
⇒ (9/20) of (A - B) = (3/10) of (A + B)
⇒ (9/2) of (A - B) = 3 of (A + B)
⇒ 9(A - B) = 6(A + B)
⇒ 9A - 9B = 6A + 6B
⇒ 3A = 15B
⇒ B/A = 3/15 = 1/5
⇒ B = (1/5) × A
∴ B = (1/5) × 100% of A = 20% of A

So B is 20% of A