You can turn 5 into 10/2 and add to x/2 then you need to use simple algebra to left the x alone in the equation so you need to multiply both sides by 2 so you get 2y=10+x then you need to subtract both sides a 10 so 2y-10=x now change the x to f'(x) and y to x so: f'(x)=2x-10
