Math
posted by Nena .
The area of trapezoid is h( b1+b2)/5,
where h is the altitude, and b1 and b2 are the lenghts of the parallel bases. If trapezoid has an altitude of 5 inches, an area of 55 square inches , and one base 12 inches long, what is the lenghth, in inches, of its other base?
Please for some sugesstions.

A=h( b1+b2)/2,
h=5
b=12
A=55
=>
55=5(12+b2)/2
Solve for b2.