(12+r)-2(r+1)=3

Solution for (12+r)-2(r+1)=3 equation:

Simplifying
(12 + r) + -2(r + 1) = 3

Remove parenthesis around (12 + r)
12 + r + -2(r + 1) = 3

Reorder the terms:
12 + r + -2(1 + r) = 3
12 + r + (1 * -2 + r * -2) = 3
12 + r + (-2 + -2r) = 3

Reorder the terms:
12 + -2 + r + -2r = 3

Combine like terms: 12 + -2 = 10
10 + r + -2r = 3

Combine like terms: r + -2r = -1r
10 + -1r = 3

Solving
10 + -1r = 3

Solving for variable 'r'.

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

Add '-10' to each side of the equation.
10 + -10 + -1r = 3 + -10

Combine like terms: 10 + -10 = 0
0 + -1r = 3 + -10
-1r = 3 + -10

Combine like terms: 3 + -10 = -7
-1r = -7

Divide each side by '-1'.
r = 7

Simplifying
r = 7