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### Question

If 4% of A + B = 9% of A - B, then what percent of B is A?

**A**

$2{3/5}$ %.

**B**

$4{1/2}$ %.

**C**

$1{1/7}$ %.

**D**

4 %.

**Soln.**

**Ans: a**

We have been given 4% of A + B = 9% of A - B, so ${A + B}/{A - B}$ = $9/4$. By componendo and dividendo, ${(A + B) + (A - B)}/{(A + B) - (A - B)}$ = ${9 + 4}/{9 - 4}$, which gives $A/B$ = $13/5$ = ${13/5}$, which is same as: $2{3/5}$%