explanation: you have to do inverse operation, so subtract 25 and -25 and then on the other side you do 40-25, which equals 15. After that you get -3x=15 and divide -3 on both sides.
The answer will be -5 What ever you do to one side you do to the other
First subtract 25 from itself and do the same to the total 25-3x=40 -3x=15
Next divide -3 from itself and the total ( keep in mind that when you multiply or divide a negative by a positive the answer will be a negative) -3x=15 X=-5
