1.
6 elevi _________ 20%
x elevi _________ 80%
x=24 elevi nu merg in tabara
2.
4 elevi la olimpiada ________ 12,5%
x elevi in clasa ____________ 100%
x=32 elevi in clasa
3.
a=30
30____________ 75%
b ____________ 100%
b=40
=>M.a.=(30+40)/2=35
4.
30a/100 - 5 = 52/10
30a-500=520
30a=1020 =>a=34
5.
25a/100 x 4a/100 = 1 sau a/4 x a/25 = 1 sau a²/100 = 1 =>a²=100 =>a=10