3(3r+1)-(r+4)=13

Solution for 3(3r+1)-(r+4)=13 equation:

Simplifying
3(3r + 1) + -1(r + 4) = 13

Reorder the terms:
3(1 + 3r) + -1(r + 4) = 13
(1 * 3 + 3r * 3) + -1(r + 4) = 13
(3 + 9r) + -1(r + 4) = 13

Reorder the terms:
3 + 9r + -1(4 + r) = 13
3 + 9r + (4 * -1 + r * -1) = 13
3 + 9r + (-4 + -1r) = 13

Reorder the terms:
3 + -4 + 9r + -1r = 13

Combine like terms: 3 + -4 = -1
-1 + 9r + -1r = 13

Combine like terms: 9r + -1r = 8r
-1 + 8r = 13

Solving
-1 + 8r = 13

Solving for variable 'r'.

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

Add '1' to each side of the equation.
-1 + 1 + 8r = 13 + 1

Combine like terms: -1 + 1 = 0
0 + 8r = 13 + 1
8r = 13 + 1

Combine like terms: 13 + 1 = 14
8r = 14

Divide each side by '8'.
r = 1.75

Simplifying
r = 1.75