Question

Un elev are o suma de bani.Dupa ce dubleaza aceasta suma cheltuieste 5 lei.Dubleaza suma ramasa si cheltuieste 10 lei.D4ubleaza din nou suma ramasa si cheltuieste 160 de lei.Elevul constata ca mai are 200 de lei.Calculati suma initiala.

Answer 1

x=suma initiala
[(x*2-5)*2-10]*2-160=200
[(x*2-5)*2-10]*2=360
(x*2-5)*2-10=180
(x*2-5)*2=190
x*2-5=95
x*2=100
x=50 lei