I have tried to solve it by bulding a equation. But, my answer is differing from the answer given in the book.

Question

A bottle $\frac34$ filled with a liquid weighs $\frac32 \text{ kg}$. The liquid alone weighs $\frac34 \text{ kg}$ more than the empty bottle. If the bottle is completely filled, how will the contents weigh?

Answer 1

Let the bottle have weight $x$ and liquid when full have weight $y$. We get $x+\frac{3}{4}y = \frac{3}{2}$ and $\frac{3}{4} y = x + \frac{3}{4}$. Solving gives us $x = \frac{3}{8}$ and $ y = \frac{3}{2}$. If the bottle is completely filled, we have the weight as $x+y = \frac{15}{8}$.