remember, you can do anything to an equation as long as you do it to both sides
I will justify each step and provide reasoning
step 1: we distributed, the distaibution is correct
step 2: we minused 2x from both sides, correct
step 3: ????? how did we get from x to 5x
also, 15+35=35, but we need to minus the 15 from both sides, not add
step 3 is the first wrong step