Докажите примитивность строения животнных, имеющих первичную полость

а)Упрости выражения А и В и найди их значения при одном и том же значении переменной а,если :

А=2,4*(5а)*0,1;

В=2,4а+а-0,2а ;

а=0,25.

б)Определи ,на сколько процентов значение А меньше, чем значение В.                              

У теплового двигателя,работающего по циклу Карно,температура нагревателя 500 К, а температура холодильника 300 К . Рабочее тело за один цикл получает от нагревателя 40 кДж теплоты. Какую работу совершает при этом рабочее тело двигателя?

(P.S помимо решения,прошу оставить подробные комментарии,чтобы я могла разобраться,заранее благодарю)

Children's writer Michael Morpurgo tells a very enjoyable story. If you have not yet discovered his books, you will be surprised. The Amazing Story of Adolphus Tips, for example, was published earlier this year.

Lily Tregenze who is 12, lives on a farm in the village of Slapton with her mother and grandfather. It's 1943, the middle of the Second World War, and her father is away in the army. Lily's life centres on her local school, currently filled with people from London sent to the country for safety, and Tips, her beloved cat. Tips keeps having kittens. But one of Lily's parents always drowns the kittens, to Lily's despair, because they cannot keep and feed a lot of cats. Then, when they have to move to their Uncle George's farm to make way for the army, Tips disappears. For months it is only the kindness of a young American soldier and his army friend who help Lily search for her cat, that helps her get through the many changes and challenges in her life. And there's a lovely twist at the end — which I shan't spoil for you — as the story shoots forward 60 years.

If you like The Amazing Story of Adolphus Tips then you will probably also enjoy Michael Morpurgo's Kensuke's Kingdom, Billy the Kid, Private Peaceful and many others.

Michael was Children's Laureate* from 2003 to 2005, an honour which involves telling as many people as possible how important children and children's books are. lie followed Quentin Blake and Anne Fine. Jacqueline Wilson was Children's Laureate until 2007.

As well as being an author, Michael Morpurgo, with his wife Clare, runs a charity called Farms for City Children. It enables groups of children to holiday in Devon, in the south west of England, or Wales.

The Amazing Story of Adolphus Tips by Michael Morpurgo. Published in hardback by Harper Collins. Due out in paperback in February 2006. Also available as an aucliobook, set of 3 CDs read by Michael Morpurgo and actress Jenny Agutter. Duration three hours.

1.Read the review and say in 2-3 sentences what ut is about.

2. The author describes what the book is about. Find this extract and read it aloud.

3. Who helped Lily when her cat disappeared?

4. Why is it an honour to be Children's Laureate?

плиз! стих небольшой очень надо