中一問題搞不懂= =

識少少都可以答！！

A wholesaler a set of Hi-Fi to a retailer for 20% higher than the cost. The retailer thwn sells it to a customer for $6480 and makes a profit of 35%.
呢條題目我的理解是:
第一句我吾明= =。零售商然后用$6480賣給一個用戶并且獲得35%盈利。

1. Find the cost of set of Hi-Fi for the retailer.
（找出HI-FI的成本？）
2. Find the cost of the set of Hi-Fi for the wholesaler.
3. If the wholesaler sells the set of Hi-Fi to the customer directly for $6000,find the percentage profit.



Three years ago, there were 200 members in a club, and the annual membership fee for each member was $4000.
1. Find the membership fee income of the club three years ago.
2. If the number of members in the club decreases by 20% but the annual membership fee for each member increases by 50% this year as compared with three years ago, how many members are there in the club this year? What is the annual membership fee for each member this year? By what percentage is the membership fee income of the club this year more than that three years ago?

After Cindy has given 5 drawing books to her brother, the number of drawing books with her decreases by 25%.How many drawing books does Cindy originally have?


A tin of tea mixture is formed by mixing three types of tea, A, B and C, of which 40% is tea A, 25% is tea B and the weight of tea C is 560g.
1.Find the weight of the tea mixture.
2.Find the respective weights of tea A and tea B in the tea mixture.
3.It is known that tea A, tea B and tea C cost $15,$18 and $20 per kg respectively. Find the cost of the tea mixture.


The monthly salary of Mandy is $25000. It is known that she spends 40% of her salary on the mortgage, and 30% of the rest of her salary on supporting her parents each months. If Mandy saves the rest after her monthly expenses of $6000, how much does she save each month?



There are 80 coloured pencil in a drawer, of which 10% are red, 15% are yellow, 20% are blue, and the rest are in other colours. How many coloured pencils are in other colours?