Answer:
b₁ = 2A/h - b₂
Step-by-step explanation:
[tex]a = \frac{h(b_1 + b_2)}{2}\\2a = h(b_1 + b_2)\\\frac{2a}{h} = b_1 + b_2\\b_1 = \frac{2a}{h} - b_2[/tex]
