Question

how do you solve f + 15 = 35

Answer 1

So what we do to one side of the equal sign, we must do to the other side as well.

We want to solve for f, so we need to subtract 15 on both sides of the equal sign in order to get f alone by itself on the left side:

$f=20$

So now we know that f = 20.

Answer 2

f + 15 = 35

Isolate the variable (f). Note the equal sign. What you do to one side, you do to the other.

Subtract 15 from both sides

f + 15 (-15) = 35 (-15)

f = 35 - 15

Simplify

f = 20

f = 20 is your answer

hope this helps