Question

The sum of twice a number and 15 is-42

Answer 1

The equation is -42=2a+15
I just picked the variable to be a
Now I would divide 2a by 2 to make it just a
And divide -42 by 2 to make it -21. Then you would have -21=a+15
Subtract 15 from 15 to cancel it out
And then subtract 15 from -21 to get
-36=a
the variable is -36