Answer:
FIRSTLY, simplify!
r = 5 * (b-2)
1) Solve whats "surrounding" the parenthesis / simplify it. Distribute TIMES 5 on whats inside the brackets; b and -2.
(5*b = 5b AND 5* -2 = -10)
r = 5b - 10
2) Rewrite the equation as 5b - 10 = r. Next, to get rid of whats beside the "5b" (since we want to know what b is), add 10 to both sides. The equation *currently* looks like this:
5b = r + 10
Now, divide each term by 5 (a term is a part of an algebraic expression thats separated by a plus or minus; like 5b, 10, and r).
5b/5 = r/5 + 10/5
Now, simplify the right side of the equation (5b/5 = b).
b = r/5 + 10/5
Then, simplify 10/5 on the left side of the equation (10/5 = 2).
b = r/5 + 10/5
Finally, that leaves us with r/5; which cannot be further simplified.
b = r/5 + 2
Hope I helped ^^