(r-42.50)+(r+42.50-15)=

Solution for (r-42.50)+(r+42.50-15)= equation:

Simplifying
(r + -42.50) + (r + 42.50 + -15) = 0

Reorder the terms:
(-42.50 + r) + (r + 42.50 + -15) = 0

Remove parenthesis around (-42.50 + r)
-42.50 + r + (r + 42.50 + -15) = 0

Reorder the terms:
-42.50 + r + (42.50 + -15 + r) = 0

Combine like terms: 42.50 + -15 = 27.5
-42.50 + r + (27.5 + r) = 0

Remove parenthesis around (27.5 + r)
-42.50 + r + 27.5 + r = 0

Reorder the terms:
-42.50 + 27.5 + r + r = 0

Combine like terms: -42.50 + 27.5 = -15
-15 + r + r = 0

Combine like terms: r + r = 2r
-15 + 2r = 0

Solving
-15 + 2r = 0

Solving for variable 'r'.

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

Add '15' to each side of the equation.
-15 + 15 + 2r = 0 + 15

Combine like terms: -15 + 15 = 0
0 + 2r = 0 + 15
2r = 0 + 15

Combine like terms: 0 + 15 = 15
2r = 15

Divide each side by '2'.
r = 7.5

Simplifying
r = 7.5