แบบฝึกหัด 1.2 ข้อ 3,4,9,10 3. x + 7 = 8 3x + 2 = 5 4. x + 2y – 1 = 0 2x + 4y – 5 = 0 9. 2x – 3y = 5 -6x + 9y = -12 1 10. x - y =2 2 Y – 2x = -4