A=1/2 h (b1 + b2 ) .. solve for b2
First, multiply both sides of the equation by 2.
2A=h(b1 + b2)
Now divide both sides by h.
2A/h = b1 + b2
Finally, subtract B from both sides.
(2A/h) - b1 = b2
This can be simplified to
b2 = 2A-hb1 / h
The number 1 , i cant see the first letter
