Combine like terms, 2x + -7x = -5x.
Now you have -5x + 6 = 21.
subtract 6 from both 6 and 21, the 6 cancels out and 21-6=15.
You’re left with -5x=15
Divide 5 on both sides, -5 cancels out, and you’re left with
x=-3
sorry this was messy and i hope this made sense!
