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2014-09-13T12:47:26+03:00
A+b+c=21

20% din a= 20/100 *a= 1/5 *a= a/5

25% din b= 25/100 *b= 1/4 * b= b/4

30% din c= 30/100 * c= 3/10 *c= 3c/10

a/5 ; b/4 ; 3c/10 dp  cu 1/2 ;  35  ; 48/1

a/5/1/2=b/4/35= 3c/10/48/1=k

a/5 * 2/1 = b/4 * 35/1= 3c/10 * 1/48=k

2a/5= 35b/4 = c/160=k

2a=5k => a= 5k/2

35b=4k => b= 4k/35

c=160k

5k/2 +4k/35 +160k=21    aducem la acelasi numitor (70)

175k + 8k + 5600k= 1470

5783k=1470

k=0,25

a=5*0,25/2= 0,625

b=4*0,25/35= 2,85

c= 160*0,25=40
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