求助 大牛两道题

mjfanshome

154. When positive integer n is divided by 3, the remainder is 2; and when positive integer t is divided by 5, the remainder is 3. what is the remainder when the product nt is divided by 15?
            

1) n-2 is divisible by 5

2) t is divisible by 3

答案：c

156. Amount charged Percent Bonus
            

$0.01 to $1,000.00         0.5

$1,000.01 to $3,000.00     1.0

$3,000.01 to $ 6,000.00    1.5

$6,000.01 to $10,000.00    2.0

At the end of each year, a certain credit card company pays a bonus to each of its credit card holders based on the amount, up to $100,000, that the card holder charged throughout the year. A 0.5 percent bonus is paid on the first $1,000 charged; a 1.0 percent bonus is paid on the next $2,000 charged and so on, as indicated in the table above. What is the maximum annual bonus, in dollars?

答案：150$

chenjianhong

不是NN，

第一题：n=3a+2,t=5b+3,nt=(3a+2)(5b+3)=15ab+9a+10b+6

第一个条件：n-2=5z,所以3a+2=5z+2,得出3a=5z,所以9a=15z,代入第一题的式中，推不出

第二个条件同理，将两个条件结合推出余数是6，选c

第二题，你把1000*0.5%+2000*1%+3000*1.5%+4000*2%可得到答案