Question

proba adunarii si scaderii

Answer 1

a + b = c proba: c - a = b, c - b = a 
a - b = c  proba b + c = a, a - c = b 
Sper ca te-am ajutat 

Answer 2

$T1+T2=S$
$Proba~adunarii=S-T2=T1,~~S-T1=T2$
$Exemple:1+5=6,~6-5=1,~6-1=5$

$T1-T2=S$
$Proba~scaderii=S+T2=T1,~~T1-S=T2$
$Exemple:5-2=3,~~3+2=5,~~5-3=2$