Question

dupa doua majorari succesive,prima de 5 % si a doua de 8%,un album costa 56,70 lei.care a fost pretul initial?

Answer 1

[100+5]/100 ·x=y;[100+8]/100 ·y=56,7[lei]
⇒108/100 ·y=56,7[lei]
⇒y=567/10/108/100
⇒y=567/10·100/108
⇒y=189/1·10/36
⇒y=21/1·10/4
⇒y=21·10/4
⇒y=21·5/2
⇒y=105/2;
⇒105/100 ·x=105/2
⇒x=105/2/105/100
⇒x=105/2·100/105
⇒x=1/2·100/1
⇒x=100/2⇒x=50[lei-pretul initial];

Answer 2

56,7 : 108 * 100 = 52,50 lei 
52,50 : 105 * 100 = 50 lei pret initial