Question

Dupa o reducere de 10%,urmata de o scumpire de 5%,un obiel costa 189 lei.
Care a fost pretul initial?

Answer 1

x-pretul initial

10% din x= 10/100 *x= 1/10 *x= x/10 -reducerea

x-x/10=  (10x-x)/10= 9x/10 -restul

5%  din 9x/10= 5/100 *9x/10= 1/20 *9x/10=  9x/200-scumpirea

9x/10 +9x/200= (180x+9x)/200= 189x/200-noul pret

189x/200=189
x=200*189/189
x=200

Answer 2

x- pret initial
 10% din x= 10/100 · x= 1/10 ·x
 
x-(1/10·x)=10x/10-x/10=9x/10(reducere)

5% din x= 5/100·x=1/20·x=x/20

9x/10+x/20=18x/20+x/20=19x/20(scumpire)

19x/20=189 lei
19x=189·20
19x=3780
x=3780/19
x=198.94 lei