Let $t$ be TNYWR.

What is the area of a triangle with base $2 t$ and height $3 t+2$ ?
The area of a triangle with base $2 t$ and height $3 t+2$ is $\frac{1}{2}(2 t)(3 t+2)$ or $t(3 t+2)$.

Since the answer to (a) is 6 , then $t=6$, and so $t(3 t+2)=6(20)=120$.