1) x = 6, x − 4= 6 − 4 = 2
2) x = 8, 5x − 4= 5 × 8 − 4 = 36
3) x = 21, x − 3= 21 − 3 = 18
4) x = −5, 8x + 5= 8 × (−5) + 5 = −35
5) x = −12, 8x + 6= 8 × (−12) + 6 = −90
6) x = 3, 3x + 8= 3 × 3 + 8 = 17
7) x = 10, 6x + 6= 6 × 10 + 6 = 66
8) x = −7, 28x + 5= 28 ÷ (−7) + 5 = 1
9) x = −14, 56x + 8= 56 ÷ (−14) + 8 = 4
10) x = 9, 18x + 6= 18 ÷ (9) + 6 = 8