21r+77+4r+2.3=10.5

Solution for 21r+77+4r+2.3=10.5 equation:

Simplifying
21r + 77 + 4r + 2.3 = 10.5

Reorder the terms:
77 + 2.3 + 21r + 4r = 10.5

Combine like terms: 77 + 2.3 = 79.3
79.3 + 21r + 4r = 10.5

Combine like terms: 21r + 4r = 25r
79.3 + 25r = 10.5

Solving
79.3 + 25r = 10.5

Solving for variable 'r'.

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

Add '-79.3' to each side of the equation.
79.3 + -79.3 + 25r = 10.5 + -79.3

Combine like terms: 79.3 + -79.3 = 0.0
0.0 + 25r = 10.5 + -79.3
25r = 10.5 + -79.3

Combine like terms: 10.5 + -79.3 = -68.8
25r = -68.8

Divide each side by '25'.
r = -2.752

Simplifying
r = -2.752