F- FETE
B-BAIETI
F=25
x=numarul elevilor
F+B=X =>B=X-F
B=3/8(F+B)
B=3/8(F+X-F)
x-F=3/8(F+X-F)
x-25=3/8(25+x-25)
x-25=75/8+3/8x
x-3/8x=75/8+25 ( amplificam x cu 8 si 25 tot cu 8)
(8x-3x)/8=(75+200)/8 l :8
5x=275 l :5
x=55 ( elevi in excursie)
Sper ca te-am ajutat.
Coroana ? :D