Answer:
a) 25 = 13 + 3x
12 = 3x
x = 4
25 = 13 + 3(4)
25 = 13 + 12
25 = 25
b) 74 = 8.5x - 62
136 = 8.5x
x = 16
74 = 8.5(16) - 62
74 = 136 - 62
74 = 74
c) 34 + 12x < 76
12x < 42
x < 3.5
34 + 12(3) < 76
34 + 36 < 76
70 < 76
d) 76 ≥ 34 - 12x
42 ≥ -12x
-12x ≤ 42
x ≥ -3.5
76 ≥ 34 - 12(-3)
76 ≥ 34 + 36
76 ≥ 70
e) 3,141 = 2,718 + 42x
423 = 42x
x = 423/42 = 141/14 = 10 1/14
3,141 = 2,718 + 42(141/14)
3,141 = 2,718 + 423
3,141 = 3,141