Regula de trei simpla:
Daca 1 kg de gutui costa 5.62 lei, 0.3 kg va costa 0.3x5.62:1= 1.686
1 kg....................5.62 kg
0.3 kg...………… a
a= 0.3x5.62:1=1.686 lei
1 kg....................5.62 kg
0.29 kg…………. b
b=1.6298 lei
1 kg....................5.62 kg
0.35 kg .………… c
c=1.967 lei
a+b+c=5.2828 lei