Respuesta :

4m - 7n = 10
2m + 2n = 4 - multiply everything by -1.

4m - 7n = 10
-2m - 2n = -4 Add the 2 equations

(4m - 7n = 10)
+(-2m - 2n = -4)
-------------------------
2m - 9 n = 6.

The value of 2m - 9n would be 6.