15. 3x - 4y = - 1

5x + 2y = 7

x = 1, y = 1

Step-by-step explanation:

3x - 4y = - 1

5x + 2y = 7

If we multiply the whole second equation by 2, we get:

10x + 4y = 14

Adding this to the first equation:

10x + 4y + 3x - 4y = 14 - 1

13x = 13

x = 1

Applying this to the second equation:

5 (1) + 2y = 7

2y = 2

y = 1