1.1. In this question, all measurements are in centimetres.

The height of the triangle is $h-3$ and the height of the rectangle is $h$.

The length of the base of the triangle and rectangle are both $x$.

Write down an expression for the area of the triangle.

1.2. The area of the triangle is $15{cm}^{2}$ and the area of the rectangle is $42{cm}^{2}$.

Show that $x=4$

1.3. Find the value of $h$.