有D數學唔色!!! 中一的, 幫幫手!!! 幫得幾多得幾多!! Help!!!

1.Brian played on-line games at home. With experience values started from 0.
On the first day, he won 17experience values. On the second day, he lost 25
experience values. What are the final experience values that Brian got?

2.There are m classes in a secondary school. Each class has a boys and b girls.
Use an algebraic expression to represent the total number of pupils in the school.

3.A, B, Chave a totalof 69kg rice. If A has one third of the rice of B and B ha s 5 times as much as C. Find the amount of rice each person has.

4.In September, there are 37students in F.5C. In October, the numberof students in F.5C became 39. Find the percentage increase.(correct the answer to 3 significant figures)

5.Quiton bought a digital camera at the price of $2280. Two months later, he sold it at a loss of 7%. Find the selling priceof the camera.