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
