Question

1.Daca x supra y=5 supra 2 atunci 2x-y supra x+y este:
2.Daca 4 muncitori termina o lucrare in 15 zile,in cate zile termina aceeasi lucrare 20 de muncitori?
3.Dupa ce a cheltuit 20% din suma de bani pe care o avea,Maria mai ramane cu 80 de lei.Suma pe care a avut-o initial Maria era de:

Answer 1

1. x/y=5/2 =>x=5y/2.
x=5y/2 =>2x-y/x+y=5y-y/7y/2=4y/7y/2=8y/7y=8/7.
2. Daca 4 muncitori termina o lucrare in 15h atunci 20 de muncitori termina o lucrare in 4•15h/20=3 zile.
3. 80/100 •x=80 lei
x=100 lei(suma initiala pe care a avut-o Maria).

Answer 2

1)
[tex]\frac{x}{y}=\frac{5}{2}\\2x=5y\\x=5k\\y=2k\\ \frac{2x-y}{x+y}=\frac{5k*2-2k}{5k+2k}=\frac{10k-2k}{7k}=\frac{8k}{7k}\\ Simplificam\ cu\ k\\=\frac{8}{7}[/tex]
2)
4 muncitori....15 zile
1 muncitor.....15*4=60 zile
20 muncitori....60/20=3 zile
3)
x=suma initiala
20% din x=20/100*x=1/5*x=x/5
x-x/5=80
5x/5-x/5=80
(5x-x)/5=80
4x=80*5
4x=400
x=400/4
x=100 lei