Răspuns:
Explicație pas cu pas:
1 si 2 in poza
3.
Fie s suma cautata.
In prima zi a cheltuit 5s/8 si i-au ramas s - 5s/8 = 3s/8
in a 2-a zi a cheltuit 3/5 x 3s/8 + 15
Deci a cheltuit in cele doua zile:
5s/8 + 3/5 x 3s/8 + 15 =
5s/8 + 9s/40 + 15 =
25s+9s / 40 + 15 =
34s/40 + 15 =
17s/20 + 15.
Astfel avem:
s - 17s/20 - 15 = 15
3s/20 = 30
3s = 600
s = 200.
