In order to find b1 from your formula stated we need to do few calculations A=hb1+hb2, as you wee I multiply h with both bases( b1 and b2) I will subtract hb2 from both sides hb1=A-hb2 now I will divide my new expression by h b1=(A-hb2)/h
solve like a regular algebraic expression
A= h(b1+b2)
divide both sides by h
A/h= b1+b2
subtract b2 from both sides
A/h-b2= b1
b1= A/h-b2
hope this helps
