What is b? 3.2 = 4/5 (b-5)
I know this has already been answered, but I need a better explanation, I just does't make any sense.

b=9

Step-by-step explanation:

Rewrite the equation as 4 /5 ⋅ ( b − 5 ) = 3.2

4 /5 ⋅ ( b − 5 ) = 3.2

Multiply both sides of the equation by 5 /4  

5 /4 ( 4 /5 ⋅ ( b − 5 ) ) = 5 /4 ⋅ 3.2

Simplify both sides of the equation.

b − 5 = 4

Move all terms not containing b to the right side of the equation.

b = 9