? : 3 = 72 : 27

Express 24 : 18 : 54 in its simplest form

The age of three cousins are in the ratio 1 : 3 : 7. If the youngest cousin is 30 years younger than the eldest cousin, how old is the middle cousin?

Express 4.5% as a decimal

Express 13/20 as a percentage

Chef Wan had 300 eggs. He used 30% of them to make some sponge cakes. How many eggs did he have left?

What is 47% of 200 kg?

Mr Koh had $8000 in his bank account. The bank paid 3% interest at the end of the yaer. He did not withdraw any of his savings. How much interest did he receive at the end of the year?

All the books in a bookshop are sold at a discount of 20%. How much is the discout if the usual price of a novel is $40?

Express 3/4 as a percentage

Hana has 540 cm of ribbon. She cuts it into shorter pieces with an average length of 60 cm. How many shorter pieces of ribbon does she have?

The average price of a notebook is $6. If Sally has $150 to buy some notebooks, how many notebooks can she buy?

Andy can peel 4 potatoes in 300 seconds. At this rate, how long does he take to peel 13 potatoes?

两个质数的积一定是（ ）

15是倍数，5是因数。

花花家的电话号码是7位数，并且是2、3、5的倍数。前三位是5、6、2，且这个7位数是满足以上条件的最小的数，你知道花花家的电话号码是多少吗？

需要检测病人的体温变化情况，应选用（ ）统计图。

有19个盘子，其中1个是次品，次品比正品轻一些现在有一架天平，至少称多少次能保证把次品找出？