First off we have to add +2x to isolate 10. After that you have to add 2 to 5x. We should be left off with
10 = -3x-50
Second, you have to use the addition property of equality and add 50 to -50, after that do the same to the other side and add 50 + 10. You should be left off with
60 = 5x
Now use the division property of equality to both sides with 5 because we want to isolate the variable.