The formula for the area of a trapezoid is A=1/2h(b1+b2). How do you express b1 in terms of A,h and b2?

To express ##b1## in terms of ##A ,h and b2## multiply both side of the equation by ##2/h## to extract it on the right side of the equation then transpose ##b2##.

##2/h (A= 1/cancel2cancelh(bi + b2))cancel2/cancelh ##

##(2A)/h = b1 + b2##

##(2A)/h= b1 +b2##

##(2A)/h - b2 = b1 ##

##b1 = (2A)/h - b2##