Question

1. Pentru a recupera o intarziere un automobilist mareste viteza intiala cu 30%, ajungand astfel la 78km/h. Aflati viteza intiala

Answer 1

x-viteza initiala
marirea: x+30x/100=x+3x/10=(10x+3x)/10=13x/10
3x/10=78
x=(78·10)/3
x=260 km/h viteza initiala

verificare
260x30/100=78

Answer 2

[100+30]/100 ·y=78
⇒130/100 ·y=78
⇒y=78/130/100
⇒y=78·100/130
⇒y=78·10/13
⇒y=6·10
⇒y=60km/h[viteza initiala];