5x-y = 77x-4y = -1................2(4x-5)-3(3+4y) = 57(6y-1)-4+3x) = 21y-86​

1) {5x + y = 7,

7x − 4y = − 1;

2) {6x − 5y = 23,

2x − 7y = 13;

3) {5x − 2y = 16,

8x + 3y = 38;

4) {5x − 4y = 10,

2x − 3y = − 3;

5) {4a + 6b = 9,

3a − 5b = 2;

6) {9m − 13n = 22,

2m + 3n = − 1.