1) f +b = 137
b=f-23
f+f-23=137
2f-23=137
2f=137+23
2f=160
f=160:2
f=80 fete
b=80-23=57 baieti
2) m+p=120
p=2m-12
m+2m-12=120
3m-12=120
3m=120+12
3m=132
m=132:3
m=44 meri
p = 2*44-12=88-12=76 pruni
3)
a+b=42
a=b:6
b=6a
a+6a=42
7a=42
a=42:7
a=6 probleme (prima zi)
b=6*6=36 probleme (a doua zi)