4(1.2b+3.7)-2.8=5.2b

Distribute the 4 on the left side of the equation:

4(1.2b) + 4(3.7) - 2.8 = 5.2b

Simplify:

4.8b + 14.8 - 2.8 = 5.2b

Combine like terms:

4.8b + 12 = 5.2b

Subtract 4.8b from both sides:

12 = 0.4b

Divide by 0.4 on both sides:

b = 30

Therefore, b = 30.