Happy Halloween! My eighth grader needs some help with literal equations. Done several of them already, but stuck on this one. Thank you all so much!

Answer:
(2A/h) - b1 = b2
Step-by-step explanation:
A = 1/2h (b1 + b2)
1. Multiply by 2 on both sides
2A = h (b1 + b2)
2. Divide by h on both sides
2A/h = b1 + b2
3. Subtract b1 on both sides
(2A/h) - b1 = b2
DONE