Solve.

2x + 6 - 7x = 21

-7x + 2x (add common factors)

-5x+6+21 (what happen to one side happens to the others

-5x=21 (divide by five)

x = - 3

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!