Answer:
2A /h -b =p
If you need it with a common denominator
(2A -bh)/h = p
Explanation:
A = 1/2 ( p+b)h
Multiply each side by 2
2A = ( p+b)h
Divide by h
2A/h = ( p+b)h/h
2A/h = ( p+b)
Subtract b
2A/h -b = p+b -b
2A /h -b =p
If you need it with a common denominator
(2A -bh)/h = p