Simplify the equation to make things easier. You can either distribute the 6 or divide it from both sides of the equation. I'm going to do the first one.
3/8f+1/2=6/16f-18
Then get the variable on one side, and the number on the other.
18+1/2=6/16f-3/8f
18+1/2=3/8f-3/8f
18 1/2=0
There's no solution because the variables cancel out, and 18 1/2 doesn't equal 0.