How to solve equation 5 (4-x) = 8 (x + 5) - 46?

How to solve equation 5 (4-x) = 8 (x + 5) - 46?

5(4-x)=8(x+5)-46
20-5x=8x+40-46
-13x=-26
13x=26
x=2
It's very simple. Don't you work out negative numbers, so you can't? Can't negative numbers become positive numbers just by reversing them?