Step-by-step explanation:
A = ½ h (b₁ + b₂)
Multiply both sides by 2:
2A = h (b₁ + b₂)
Distribute the h:
2A = h b₁ + h b₂
So the second option is not correct.
Instead of distributing, divide by h:
2A/h = b₁ + b₂
Subtract b₂ from both sides:
b₁ = 2A/h − b₂
Third option is correct.
Next, use common denominator to combine.
b₁ = 2A/h − h b₂/h
b₁ = (2A − h b₂) / h
Factor out 2.
b₁ = 2 (A − ½ h b₂) / h
Fourth option is correct.
