Question

O persoana a cheltuit o suma de bani astfel: in prima zi $\frac{1}{2}$ din suma, a doua zi $\frac{1}{5}$ din rest, a treia zi $\frac{1}{2}$ din noul rest si a patra zi ultimii 50 lei. Aflati suma initiala.

Answer 1

x=suma initiala
x/2 =ziua 1
x-x/2=x/2 =rest
x/2 *1/5=x/10 =ziua 2
x/2-x/10=(5x-x)/10=4x/10=2x/5=rest
2x/5 *1/2=2x/10
x/2+x/10+2x/10+50=x
5x+x+2x+500=10x
2x=500
x=250 lei