Answer:
See Explanation
Step-by-step explanation:
[tex]A = \frac{1}{2} h(b_1+b₂) \\ \\ 2A = h(b_1+b₂) \\ \\ \frac{2A}{h} = b_1+b₂ \\ \\ \frac{2A}{h} -b₂ = b_1 \\ \\ \frac{2A -b₂ h }{h} = b_1 \\ \\ \huge \red{ \boxed{b_1 = \frac{2A -b₂ h }{h} }}[/tex]
