a=probleme Mihaela
a-120=probleme Andreea
a/(a-120)=7/4
4a=7a-840
3a=840
a=280 probleme Mihaela
a-120=160 probleme Andreea
I------I------I------I------I------I------I------I probleme Mihaela
I------I------I------I------I 120 probleme Andreea 120 diferenta intre Mihaela si Andreea
120:3=40
7x40=280 probleme Mihaela
280-120=160 probleme Andreea