Help me solve this equation..

Let a be the area of the triangle
Let b be the area of the parallelogram
[tex]a = \frac{16 \times 9}{2} = 72 \: cm {}^{2} [/tex]
[tex]b = 30h \: cm {}^{2} [/tex]
Given that b is 5 times larger than a
b=5a
[tex]30h = 5(72)[/tex]
[tex]h = \frac{360}{30} = 12 \: cm[/tex]