5 карандашей стоят на 15 р дешевле, чем 3 ручки и 2 карандаша. На сколько рублей карандаш

5 карандашей стоят на 15 р дешевле, чем 3 ручки и 2 карандаша. На сколько рублей карандаш дешевле ручки?
- Предмет:
  Математика
- Автор:
  mikey
- 5 лет назад

Ответы 1

x- карандаши, y- ручки. 5x=3y+2x-153x-3y=-1515=3y-3x $\left \{ {{15=3y-3x} \atop {15+3x=3y}} ight. \left \{ {{15=3(15+3x)-3x} \atop {15+3x=3y}} ight. \left \{ {{15=45+9x-3x} \atop {15+3x=3y}} ight. \left \{ {{15-45=6x} \atop {15+3x=3y}} ight. \left \{ {{-30=6x} \atop {15+3x=3y}}$ т.к цена не может быть отрицательной то x=515+3*5=3yy=10ручка-10рубкарандаш-5рубОтвет:ручка на 5 руб дороже карандаша
- Автор:
  dreamervaughn
- 5 лет назад
- 0
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TEST form 10
1. Choose and fill in the gaps
1. It … his first voyage that day. He …to New York many times.
a) were not/ was already
b) was/ been already
c) wasn’t/ had already been
d) was not/ was already
2. Nurses _____ after people in hospital.
a) looks
b) is looking
c) will look
d) look
3. He _____ some new shoes last month.
a) bought
b) buying
c) buy
d) buys
4. He ... his work yet.
a) didn't finish
b) haven't finished
c) hasn't finished
d) hadn't finished
5. While I _____ this morning, I _____ my money. I don’t know how.
a) shopped / lose
b) was shopping / lost
c) shopped / was losing
d) shop / lose
6. She …a member of our organization for more than 10 years.
a) has/be
b) have/been
c) was
d) has/been
7. She … only for half a year for an employer (нахозяина) before she was fired.
a) has/worked
b) had/worked
c) worked
d) was working
8. I _____ lots of books every year.
a) will read
b) am reading
c) read
d) am going to read
9. … your bother … off the table before I turned up?
a) have/ felled
b) did/ fell
c) had/ fallen
d) did/ fall
10. I _____ for my things when I ____ someone call my name.
a) paid / was hearing
b) pay / heard
c) was paying / hear
d) was paying / heard
11. Oh, someone _____ in my seat!
a) is sitting
b) sits
c) will sit
d) sit
12. What _____ in your free time?
a) are you doing
b) do you do
c) you do
d) are you do
13. I’m looking for Kate. Can you tell me where she is at the moment? – I don’t know, she … just … .
a) have/leved
b) have/left
c) has/leave
d) has/left
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b) did / will not come
c) do / didn’t / come
d) have / done / came
e) will / do / doesn’t come
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b) bought / visit
c) buys / visited
d) were buying / should visit
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A) gave
B) give
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5 карандашей стоят на 15 р дешевле, чем 3 ручки и 2 карандаша. На сколько рублей карандаш дешевле ручки?

Ответы 1

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