So,
Here we have the following trapezoid:
Remember that the area of a trapezoid can be found if we apply the following formula:
[tex]A=\frac{1}{2}(\text{base}1+\text{base}2)\cdot\text{height}[/tex]Where bases 1 and 2 are the greater and smaller bases respectively.
So, if we replace:
[tex]\begin{gathered} A=\frac{1}{2}(15+4)\cdot4 \\ A=\frac{1}{2}(19)\cdot4 \\ A=9.5\cdot4 \\ A=38 \end{gathered}[/tex]So the area is 38cm^2.