39 + a = 71
a = 71 - 39 → aflu termenul necunoscut folosind proba adunarii prin scadere
a = 32
Verific: 39 + 32 = 71
______________________
63 - a = 28
a = 63 - 28
a = 35
Verific: 63 - 35 = 28
___________________
a + 46 = 62
a = 62 - 46
a = 16
Verific: 16 + 46 = 62
__________________
a - 35 = 37
a = 37 + 35
a = 72
Verific: 72 - 35 = 37
