You can put this solution on YOUR website! First use the distributive property to remove the parentheses. Be careful of the negative in front of the 5.
2x - 5x - 15 = 81
Combine like terms on the left side:
-3x - 15 = 81
Get all the non-x terms on the right side, so add +15 to each side:
-3x - 15 + 15 = 81 + 15
-3x = 96