2(r-7)-(r-8)=3

Solution for 2(r-7)-(r-8)=3 equation:

Simplifying
2(r + -7) + -1(r + -8) = 3

Reorder the terms:
2(-7 + r) + -1(r + -8) = 3
(-7 * 2 + r * 2) + -1(r + -8) = 3
(-14 + 2r) + -1(r + -8) = 3

Reorder the terms:
-14 + 2r + -1(-8 + r) = 3
-14 + 2r + (-8 * -1 + r * -1) = 3
-14 + 2r + (8 + -1r) = 3

Reorder the terms:
-14 + 8 + 2r + -1r = 3

Combine like terms: -14 + 8 = -6
-6 + 2r + -1r = 3

Combine like terms: 2r + -1r = 1r
-6 + 1r = 3

Solving
-6 + 1r = 3

Solving for variable 'r'.

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

Add '6' to each side of the equation.
-6 + 6 + 1r = 3 + 6

Combine like terms: -6 + 6 = 0
0 + 1r = 3 + 6
1r = 3 + 6

Combine like terms: 3 + 6 = 9
1r = 9

Divide each side by '1'.
r = 9

Simplifying
r = 9