If 1.5a = 0.04b then b - ab + a is equal to?

Answer: Option A

$$\begin{array}{rl}& 1.5a=0.04b\\ & \frac{a}{b}=\frac{0.04}{1.5}=\frac{4}{100}\times \frac{10}{15}=\frac{2}{75}\\ & \text{Let }a=2x,b=75x\\ & \therefore \frac{b-a}{b+a}=\frac{75x-2x}{75x+2x}=\frac{73}{77}\\ & \\ & \mathbf{Alternate}:\\ & \frac{a}{b}=\frac{0.04}{1.5}\\ & \therefore \frac{b-a}{b+a}=\frac{1.5-0.04}{1.5+0.04}\\ & =\frac{1.46}{1.54}\\ & =\frac{73}{77}\end{array}$$