#### Answer

$\text{Harry's brother is}$ $2y-3$ $\text{years old.}$

#### Work Step by Step

Let us start at Harry's age, $y$. First, we multiply this age by $2$, for the problem says "twice as old", giving us $2y$. Then, we must subtract $3$ from this product, for it says "three less than twice...", giving us $2y-3$.