Respuesta :

Let's eliminate the variable x first.  To do this, multiply the first row of this system by 5 and mult. the second row by -7:

7x-5y=14      =>    35x - 25y = 70

5x+7y=64    =>   -35x - 49y = -448

                           -------------------------

                                   - 74y = - 378.  Then y = 378/74 = 5.11.

Subbing 5.11 for y in the first equation, we get:  7x - 5(5.11) = 14.  Then:

7x = 14+25.55 = 39.54.  Dividing both sides by 7:    x = 39.54/7 = 2.71

The solution is (2.71, 5.11).  If this does not agree with any of your answer choices, please double check to ensure that you've copied down the original problem correctly.