Răspuns:
a) 460 - 10 × a = 60
10 × a = 400
a = 40
b) (58 × a - 80) : 25 = 20
58 × a - 80 = 500
58 × a = 580
a = 10
c) [(a + 54) × 4 + 6] × 4 = 984
(a + 54) × 4 + 6 = 980
(a + 54) × 4 = 972
a + 54 = 243
a = 189
d) 929 - (512 - 144 : a ) × 2 = 1
(512 - 144 : a) × 2 = 928
512 - 144 : a = 464
144 : a = 48
a = 3
e) (420 : a) × 4 + 24 = 44
(420 : a) × 4 = 20
420 : a = 5
a = 84