Răspuns :
a - b = 40
a : b = 4 rest 1
a = 4 × b + 1
4 × b + 1 - b = 40
3 × b + 1 = 40
3 × b = 40 - 1
3 × b = 39
b = 39 : 3
b = 13
a = 4 × 13 + 1
a = 52 + 1
a = 53
a : b = 4 rest 1
a = 4 × b + 1
4 × b + 1 - b = 40
3 × b + 1 = 40
3 × b = 40 - 1
3 × b = 39
b = 39 : 3
b = 13
a = 4 × 13 + 1
a = 52 + 1
a = 53