1. 5+5+5+5, 5+5+5+5, 5+5+5+5 = 60+5+5+5=75+2+2=79
Wynik 5×15+2×2 = 79 zł
Odpowiedź: Basia ma 17 monet, 15 monet 5 zł i 2 monety 2 zł.
2. Krzyś: 30 lat Kasia: 10 lat
2(x+10) = 3x + 10
2x + 20 = 3x + 10
-x = -10
x = 10, 3x = 3·10 = 30
3. Basia = 15 lat Ewa = 10 lat
x+y = 25 x=y+5