You want to isolate x.
First, lets move 8.60 to th other side:
40 + 8.60 = 7.25x => 48.60 = 7.25x
Now, divide left and right by 7.25
48.60/7.25 = 7.25x/7.25 => x ≈ 6.7 (rounded)
Tip: throw the equation in wolfram alpha.
I'm sure you can work out the other one.
