Răspuns:
Explicație pas cu pas:
3.
S = suma initiala
Prima zi = 3S/20
A doua zi = 6S/8
Diferenta dintre suma cheltuita a doua zi si cea cheltuita in prima zi
6S/8 - 3S/20 = 240 dolari
30S/40 - 6S/40 = 240 dolari
24S/40 = 240 dolari
S = 240*40/24 = 400 dolari
In primele doua zile a cheltuit 3S/20 + 6S/8 = 6S/40 + 30S/40 = 36S/40
A treia zi a cheltuit S - 36S/40 = 40S/40 - 36S/40 = 4S/40 = S/10
S/10 = 400/10 = 40 dolari
