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2014-04-26T00:57:56+03:00
A+b+c+d=345
b= 80% din a= 80/100 *a=  8/10 = 8a/10
c=75%  din b= 75/100*8a/10=  60a/100=  6a/10
d=60% din c= 60/100*6a/10=  6/10=  9a/25

a+8a/10+ 6a/10  +9a/25=  345  aducem la acelasi numitor
50a+40a+18a+30a=17250
138a=17250
a=125
17 4 17
2014-04-26T01:01:20+03:00

a+b+c+d=345

b=(80/100)*a

c=(75/100)*b⇒c=(75/100)*(80/100)*a

d=(80/100)*c⇒d=(60/100)*(75/100)*(80/100)a

a+(80/100)*a+(75/100)*(80/100)a+(60/100)*(75/100)*(80/100)a=345⇒a+8/10a+6/10a+9/25a=345⇒(aducem la acelasi numitor, numitorul comun fiind 250)⇒250a+200a+150a+90a=86250⇒690a=86250⇒a=125

Solutie:

a=125

b=0,8*8=0,8*125=100

 c=0,75*b=0,75*100=75

 d=0,6*c=0,6*75=45