Решите систему уравнений:9х+13у=31

                                                    18х-5у=31

Даны вещества: Оксид натрия, азотная кислота, оксид углерода (4), хлорид бария, вода. Какие из этих веществ будут взаимодействовать с гидроксидом калия? Напишите уравнения соответствующих реакций. Туплю на этом задании

I. Find the word with the same or similar meaning.

Example:  research – c)

                a) an experiment        b) an achievement       c) an exploration

1) cold

     a) misty       b) windy       c) cool

2) miserable

     a) hard      b) terrible          c) nasty

3) astronaut

     a) spaceman       b) space travel        c) spaceship

4) to break

      a) to damage     b) to destroy       c) to hurt

5) a problem

      a) research          b) information         c) trouble

II. Choose the word which best completes the sentence.

Example:  I'm sure that one day the scientists will … most of medical problems.

               a) take     b) solve        c) explore

                 I'm sure that one day the scientists will solve most of medical problems.  

1. Every year different natural disasters such as earthquakes, hurricanes, tornadoes and volcanic eruptions happen on our … .

    a) star               b) satellite        c) planet

2. Jules Verne throws his heroes into … by means of a huge gun.

    a) distance       b) space         c) the Moon

3. The terrible hurricane had … all the houses by that time.

    a) destroyed        b) damaged          c) broken

4. We have been doing … into space for many years already.

    a) damage        b) research            c) disasters

5. … is a long period of dry weather when there is not enough water.

    a) flood          b) earthquake            c) drought

6. He climbed into his … and in a few minutes he was out in space.

    a) spacesuit          b) spaceship          c) satellite

7. InBritainpeople often start conversations by talking about the … .

    a) seasons           b) weather               c) disasters

8. The satellite was launched … space three days ago.

    a) in        b) into        c) to

9. I shake … a leaf before every exam.

    a) like       b) with         c) from

10. I haven't been to any parties … a long time.

    a) since         b) for

III.  The word in capitals above each of the following sentences can be used to form a word that fits suitably in the blank space. Fill each blank in this way.

Example:  DISASTER

More than 200 people were killed during the disastrous hurricane in 1992.

1. BRIGHT

When I arrived, the sun began to shine … .

2. FROST

It was lovely to ski down the hills inSwitzerlandand the weather was … and snowy.

3. CONSTUCT

Sergei Korolev was the … of the first spaceship.

4. DESTROY

The last earthquake in theUSAwas very … .

5. TYPE

What kind of weather is … of the northern part ofRussia?

IV. Choose the correct form of the verb.

1. He … the house before I had time to ask him anything.

    a) left         b) was leaving            c) had left

2. When I rang up Mike, he … still … the poem.

    a) did … learnt          b) was … learning            c) had learnt

3. I … to the hotel after I had sent the telegram to my relatives.

    a) returned        b) was returning           c) had returned

4. While Kate … inAmerica, she learnt a lot about a famous pop star Madonna.

    a) travelled               b) was travelling                   c) had traveled

5. When … you … receive a letter from your friend?

    a) did … receive           b) were … receiving                 c) had … received   

решите пожалуйста систему линейных ур-ий: y-5=3x 2y+x=-4