Question

A=2 pie r squared + 2 pie r h solve for h

Answer 1

A=2pie r^2 + 2pie rh so get h alone.
first take out the common factor of 2pie 2, so A=2pie r (r+h)
then divide by 2pie r, A/2pie r= r+h 
then subtract r, so (A/2pie r) - r= h