2x-7y=15-3+7y=5solve by elimination

The answer is -10 because you would cross out -7y and +7y which just leaves you with -2x and 15. For the bottom portion you would add +3 and -3 which Cancel out . And the. You add +3 to 5 which would be 8. And after that you would add down so you would add 15 + 5 = 20 than you divide -2x to both sides so you cross out -2 and -2x which will leave you with just x so then you would divide -2 and 20 which would turn into -10.