3) 58435+42315-100750 =
100750-100750 = 0
6) a+b = 90
a/b = 7 rest 2
⇒a = 7*b +2
inlocuim in prima ecuatie si avem;
7b+2+b=90
8b=90-2
8b=88
b=88/8
b=11
a = 7*b+2
a= 7*11 +2
a = 77+2
a = 79
Verificare
79+11 = 90
4). A U B ∈{0,1,2,4,5}
A intersectat B ∈{1,4}
A - B ∈{0,5}
B - A∈{2}
5) A ∈{1,3,5,6,10}
B∈{0,2,4,5,6,10}