Ipoteza de baza este ca amindoua termina simultan.
Notam:
- a numarul de operatii efectuate de maria. Asta inseamna ca maria adauga 5a margele in 3a minute
- b numarul de operatii efectuate de raisa. Asta inseamna ca raisa adauga 6b margele in 4b minute
Sint 38 margele:
5a+6b=38
Iar ca timp: 3a=4b
b=3a/4
5a+6×3a/4=38
5a+9a/2=38 |×2
19a=76
a=4, b=3
Margelele sint adaugate in 3a=4b=12 minute.
Raspuns: a. 12 minute