4x + 3y = 17 and 5x – 3y = 1

–5m + 6n = –8 and –5m + 8n = 6

2x – 7y = –9 and 6x + 7y = 57

5p – 4q = 3 and –5p – 4q = 13

6c + d = 12 and c – d = 2