急！ 请教两道数学题。(等高手赐教）

急！
        请教两道数学题。（等高手赐教）

1.       What is the total number of integers between 100 and 200 that are divisible by 3 ?

(A)  33  (B) 32  (C) 31 (D)30 (E)39

Answer should be (A) , but I don’t know why? Can any body help to explain the procedure??

2.       The market value of a certain machine decreased by 30 percent of its purchase price each year. If the machine was purchased in 1982 for its market value of $ 8000, what was its market value two years later?

(A)  $ 8000  (B) $ 5600  (C) 3200  (D) 2400 (E) 800

 Answer should be (C) ， why？？？as I could not count out the number never actual match each above selection.

My procedure as below:

(1-0.3)^ 2 *8000= 3920....

but why the answer is 3200?

200以内3的倍数有66个，100以内3的倍数有33个，相减得33个100到200之间3得倍数

第2题我也错过，看清题目decreased by 30 percent of its purchase price ，所以式子应该是8000-8000*0.3*2=3200

oh,明白拉。真是要好好看条件才是。。第二题其实就是折旧问题。谢谢！

但是现在还有一点与复利混淆的地方不是很明白，在什么情况下 是应该用 (1-0.3)^2 呢？？