-9=5(6+3r)-6(3+3r)

Solution for -9=5(6+3r)-6(3+3r) equation:

Simplifying
-9 = 5(6 + 3r) + -6(3 + 3r)
-9 = (6 * 5 + 3r * 5) + -6(3 + 3r)
-9 = (30 + 15r) + -6(3 + 3r)
-9 = 30 + 15r + (3 * -6 + 3r * -6)
-9 = 30 + 15r + (-18 + -18r)

Reorder the terms:
-9 = 30 + -18 + 15r + -18r

Combine like terms: 30 + -18 = 12
-9 = 12 + 15r + -18r

Combine like terms: 15r + -18r = -3r
-9 = 12 + -3r

Solving
-9 = 12 + -3r

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '3r' to each side of the equation.
-9 + 3r = 12 + -3r + 3r

Combine like terms: -3r + 3r = 0
-9 + 3r = 12 + 0
-9 + 3r = 12

Add '9' to each side of the equation.
-9 + 9 + 3r = 12 + 9

Combine like terms: -9 + 9 = 0
0 + 3r = 12 + 9
3r = 12 + 9

Combine like terms: 12 + 9 = 21
3r = 21

Divide each side by '3'.
r = 7

Simplifying
r = 7