Answer:
Simplifying
5r2 + 5 = 130
Reorder the terms:
5 + 5r2 = 130
Solving
5 + 5r2 = 130
Solving for variable 'r'.
Move all terms containing r to the left, all other terms to the right.
Add '-5' to each side of the equation.
5 + -5 + 5r2 = 130 + -5
Combine like terms: 5 + -5 = 0
0 + 5r2 = 130 + -5
5r2 = 130 + -5
Combine like terms: 130 + -5 = 125
5r2 = 125
Divide each side by '5'.
r2 = 25
Simplifying
r2 = 25
Take the square root of each side:
r = {-5, 5