Răspuns :
(30x10)-(4xf+50x2)=100
300 - (4f +100)=100
4f+100 = 300-100
4f+100=200
4f = 200-100
4f=100
f=100:4
f= 25
300 - (4f +100)=100
4f+100 = 300-100
4f+100=200
4f = 200-100
4f=100
f=100:4
f= 25