Solve the following system of equations 2x+7y=-57 and -6x-8y=80

I would use the process of elimination.   Divide 13 from both sides
2x+7y=-57                                                     y=-7 then plug in y to an equation
-6x-8y=80                                                    2x+7(-7)=-57    multiple
multiple the first equation by 3                 2x-49=-57    add 49 to both sides
6x+21y=-171                                              2x=-8       divide two from both sides
-6x-8y=80                                                      x=-4
combine like terms                                     So your things would be x=-4 and y=-7
13y=-91                                        And itd make the solution (-4,-7).