Question

va rog ajutati-ma la problemele 2 si 4.

Answer 1

2.
a)800_________ 100%
     20_________  x
x=2000/800=20/8=2,5%

b)50__________ 100%
     4__________  x
x=400/50=8%

c)400__________ 100%
     28__________  x
x=2800/400=7%

d)54___________ 100%
   12___________   x
x=1200/54=200/9=22,(2)%

e)2,5___________ 100%
   0,5___________   x
x=50/2,5=500/25=20%

4.
a+b=3900
12% este 12/100=3/25
8% este 8/100=2/25
3a/25=2b/25-12
3a=2b-300 =>a=(2b-300)/3
(2b-300)/3 + b = 3900
2b-300+3b=11700
5b=11700+300
5b=12000 =>b=2400 si a=1500