6+9r=21+4r

Solution for 6+9r=21+4r equation:

Simplifying
6 + 9r = 21 + 4r

Solving
6 + 9r = 21 + 4r

Solving for variable 'r'.

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

Add '-4r' to each side of the equation.
6 + 9r + -4r = 21 + 4r + -4r

Combine like terms: 9r + -4r = 5r
6 + 5r = 21 + 4r + -4r

Combine like terms: 4r + -4r = 0
6 + 5r = 21 + 0
6 + 5r = 21

Add '-6' to each side of the equation.
6 + -6 + 5r = 21 + -6

Combine like terms: 6 + -6 = 0
0 + 5r = 21 + -6
5r = 21 + -6

Combine like terms: 21 + -6 = 15
5r = 15

Divide each side by '5'.
r = 3

Simplifying
r = 3