Answer: 
Step-by-step explanation:
You can reduce the fractions, then:



Rewrite them as following:

If you subtract the first number and the second number, you obtain:

If you subtract the second number and the second number, you obtain:

Therefore, you must subtract
and
to obtain the number asked. Then, this is:

4in x 18in^2= 72 inches cubed
U will take the two diagrams
And name them A N B
U then solve the triangle by triangle