Răspunsuri

2014-08-20T13:52:48+03:00
X-lungimea drumului

20% din x=  20/100 * x= 1/5 * x=   x/ 5 - prima data

x-x/5=  (5x-x)/5=   4x/5 - restul

30% din 4x/5=  30/100 * 4x/5= 3/10 * 4x/5= 12x/50 -a doua oara

4x/5 -12x/50=  (40x -12x)/50=   28x/50 - noul rest

28x/50=560

x=50*560/28

x=50*20

x=1000
4 4 4
Cel mai inteligent răspuns!
2014-08-20T13:56:59+03:00
Notez cu x distanta drumului

prima zi :  \frac{20}{100}  * x =  \frac{x}{5}

rest: x -  \frac{x}{5}  =  \frac{5x-x}{5} = \frac{4x}{5}

a doua zi :  \frac{30}{100} *  \frac{4x}{5} =  \frac{6x}{25}

treia zi : 560 

x =  \frac{x}{5} +  \frac{6x}{25 } + 560 =  \frac{5x + 6x + 560 * 25}{25} = \frac{11x + 560 * 25}{25}

25x = 11x + 560 * 25
25x-11x=560 * 25
14x = 14000
x=14000: 14
x=1000 km
33 4 33