If 60% of (a – b) is the same as 40% of (a + b), then what percentage of a is b?

Correct option is A

Given:

60% of (a – b) = 40% of (a + b)

Solution:

$$\frac{60}{100}(a - b) = \frac{40}{100}(a + b) \\ \ \\3(a - b) = 2(a + b)\\ \ \\3a - 2a = 3b + 2b\\ \ \\a = 5b \\ \ \\\frac{b}{a} = \frac{1}{5} = 20\%$$​