Jack and his brother had 550 dollars altogether. Jack spent 60 dollars and his brother spent 30 dollars. Jack had 30 dollars more than his brother in the end. How much money had Jack at first ?

There were 72 students in Class 3A and Class 3B altogether. If 2 students were transferred from 3B to Class 3A, Class 3A would have 8 more students than Class 3B. How many students were there in Class 3B at first ?

Paul and May had 210 marbles altogether. When Paul gave May 18 marbles, both of them had the same number of marbles. How many marbles did each of them have at first ?

Carton A and Carton B had 80 apples in all. When 15 apples were transferred from Carton A to Carton B, the two cartons had the same number of apples. How many apples were there in each carton at first ?

Van and An have 180 books altogether. Van has 12 more books than An. How many books does each of them have ?

Anna and Bella have 320 dollars altogether. Bella and Tom have 360 dollars in all. Tom and Anna have 240 dollars altogether. How much does each of them have ?

There are 120 books altogether on a bookshelf. The top shelf holds 11 more books than the middle one. The bottom shelf holds 5 books fewer than the middle one. How many books are there on each shelf ?

Aloy and Ben have 150 dollars altogether. Aloy’s mother gives him another 40 dollars and Ben spends 10 dollars on a book. Ben then has 10 dollars more than Aloy. How much money does each of them have at first ?

There are a total of 660 passengers on two ships. 30 passengers alight from Ship A and 70 passengers board Ship B. As a result, the number of passengers on the two ships becomes the same. How many passengers are there on each ship at first ?

In the final match of a basketball league, the team that wins two consecutive games will be the champion. Otherwise, the team that wins three games in total will win the title. How many possible ways can a team win ?

Mrs Clancy rings her students to inform them of the cancellation of a lesson. In the first minutes, she informs Abel. In the second minute, she informs Dian, and Abel in turn informs Chloe and so on. How many students are informed of the cancellation of the lesson in 5 minutes ?

In the figure below, how many triangles can be formed using any three points ?

A street has 12 lamp-posts. In an attempt to save energy, the City Planning Department decides that only 5 lamps should be turned on at any one time. In how many ways can this be done ?

Weights of 1 g, 5 g and 8 g are placed on a balance. How many different amounts of weight can the balancee measure ?

How many times does the digit “3” appear from numbers 1 to 2009 ?