So if you use distributive property you would charge the equation to 50+10x-10=90 simplified even more it would be 10x+40=90
Subtract 40 from both sides to get 10x=50 divide both by 10 to get x=5
Go back and check work 10(5)+40=90
50+40=90
90=90
X=5
Good luck algebra is something else