x-suna primita
excursie x-x/3=(3×-×)/3=2×/3
ob. turistice 2×/3-2×/3•2/8=2×/3-×/6=(2•2x-x)/6=3x/6=x/2
suveniruri x/2×/2•2/6=x/2-x/6=(3x-x)/6=2x/6=x/3
dulciuri x/3-x/3•1/5=x/3-x/15=(5x-x)/15=4x/15
4x/15=240
×=(240•15)/4=900 lei a primit de la mama
excursii 900/3=300lei
ob. turistice (900-300)•2/8=150
suveniruri (900-300-150)•2/6=150
dulciuri (900-300-150-150)•1\5=60
chelt. neprevăzute = 240
300+150+150+60+240=900