составить из чисел 10,15,21 пару взаимо простых чисел

Задача на сложение и вычитания дробей: Одна машина может полить парк за 6 часов, а вторая - за 8 часов. Успеют ли эти машины полить парк, работая совместно в течении 4 часов?

перевести текст на русский

Is there anything more important than health? I don't think so. "Health is the greatest wealth," wise people say. You can't be good at your studies or work well when you are ill.

If you have a headache, heartache, toothache, backache, earache or bad pain in the stomach, if you complain of a sore throat or a bad cough, if you run a high temperature and have a bad cold in your head, or if you suffer from high or low blood pressure, I think you should consult a doctor. The doctor will examine your throat, feel your pulse, test your blood pressure, take your temperature, sound your heart and lungs, test your eyes, check your teeth or have your chest X-rayed.

After that he will prescribe some treatment, pills, tablets or some other medicine which we can buy at the chemist's. He will recommend you to stay in bed for some time, because there might be serious complications. The only thing you have to do is to follow his recommendations.

Speaking about doctors' recommendations, I can't help telling you one funny story.

An old gentleman came to see the doctor. The man was very ill. He complained of weakness, insomnia, memory loss and serious problems with his heart, lungs and liver. The doctor examined the patient and said that no medicine could cure his desease.

Do you want to know what the doctor's advice was?

He told his patient to go to a quiet place for a month and have a good rest. He also advised him to eat a lot of meat, drink two glasses of red wine every day and take long walks. In other words, the doctor recommended him to follow the rule: "Eat at pleasure, drink with measure and enjoy life as it is."

The doctor also said that if the man wanted to be well again, he shouldn't smoke more than one cigarette a day.

A month later the gentleman came into the doctor's office. He looked cheerful and happy. He thanked the doctor and said that he had never felt a healthier man.

"But you know, doctor," he said, "it's not easy to begin smoking at my age."

Два мяча прижаты друг к другу и мгновенно отпущены. Первый мяч отскочил за некоторое время в горизонтальном направлении на 1,2 м, а другой за это же время на 1,5 м. Найти отношение кинетической энергии первого мяча к энергии второго в момент их разъединения