Răspuns:
1.B+F=36
F=B+40B/100
F=B+2B/5
B+B+2B/5=36
2B+2B/5=36
10B+2B=180
12B=180
B=180:12
B=15 este numarul baietilor
2.Prima zi 3/8x L;
A doua zi: 30%x(L-3L/8)=30/100X(8L-3L)/8=3/10X5L/8=3L/16
A treia zi : 28km
L=lungimea drumului
L=3L/8+3L/16+28; n.c.=16
16L=6L+3L+448
16L=9L+448
16L-9L=448
7L=448
L=448:7
L=64 KM