亲爱的，帮忙解两道数学PS吧~~~不胜感激！！

zlin0222

1、 A parking garage rents parking spaces for $10 per week or $30 per month. How much does a person save in a year by renting by the month rather than by the week?
(A) $140
(B) $160
(C) $220
(D) $240
(E) $260

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 $8,000, what was its market value two years later?
(A) $8,000
(B) $5,600
(C) $3,200
(D) $2,400
(E) $800

答案分别是B&C

agnesliu

10*52-30*12=520-360=160

8000*30%=2400 2400*2=4800 8000-4800=3200

zlin0222

啊我太弱了。。想错了。。谢谢啦！！