f+(f-6)+(3f-9)=60

Solution for f+(f-6)+(3f-9)=60 equation:

Simplifying
f + (f + -6) + (3f + -9) = 60

Reorder the terms:
f + (-6 + f) + (3f + -9) = 60

Remove parenthesis around (-6 + f)
f + -6 + f + (3f + -9) = 60

Reorder the terms:
f + -6 + f + (-9 + 3f) = 60

Remove parenthesis around (-9 + 3f)
f + -6 + f + -9 + 3f = 60

Reorder the terms:
-6 + -9 + f + f + 3f = 60

Combine like terms: -6 + -9 = -15
-15 + f + f + 3f = 60

Combine like terms: f + f = 2f
-15 + 2f + 3f = 60

Combine like terms: 2f + 3f = 5f
-15 + 5f = 60

Solving
-15 + 5f = 60

Solving for variable 'f'.

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

Add '15' to each side of the equation.
-15 + 15 + 5f = 60 + 15

Combine like terms: -15 + 15 = 0
0 + 5f = 60 + 15
5f = 60 + 15

Combine like terms: 60 + 15 = 75
5f = 75

Divide each side by '5'.
f = 15

Simplifying
f = 15