Question 23481
I am quite sure in this problem that the 1 and the 2 after the two b's are SUBSCRIPTS, not exponents.


With that assumption, your equation is 
 {{{A= (1/2)*h*(b[1]+b[2])}}}, solve  for h.  


(This is the formula for the area of a trapezoid!!)
The first step is to clear the fraction by multiplying both sides by the denominator which is 2.

 {{{2*A= 2*(1/2)*h*(b[1]+b[2])}}} 
{{{2*A= h*(b[1]+b[2])}}}


Next, since h is MULTIPLIED by the quantity with the b's, you must DIVIDE both sides of the equation by that quantity:

{{{(2*A)/(b[1]+b[2])= (h*(b[1]+b[2]))/(b[1]+b[2]) }}}


Final answer is {{{h = (2A)/(b[1] +b[2])}}}


R^2 at SCC