Question

40 % din elevii unei clase prefera limba engleza, 32% dintre ei prefera matematica , iar restul de 7 elevi prefera informatica. cati elevi sunt in
clasa?

Answer 1

40/100+32/100+7=100/100
⇒7=100/100-[40/100+32/100]
⇒7=100/100-72/100
⇒7=28[la suta]
⇒7 elevi=28[la suta]
⇒28/100 ·x=7
⇒x=7/28/100
⇒x=7·100/28
⇒x=100/4⇒x=25[elevi-sunt in clasa];

Answer 2

40% + 32% = 72 %
100% - 72% = 28%
28% = 7 elevi
28%...............7 elevi
40%...............x
x = 40 * 7 : 28 = 10 elevi engleza
28%.............7 elevi
32%...............x
x = 32 * 7 : 28 =8 elevi matematica
10 + 8 + 7 = 25 elevi ia clasa