Dung and Henry works in an organization where there are paid in ratio of the work done by them. Dung can finish a task in 4 days, while Henry can finish it in 2 days. If monthly salary of Dung is ₫6,000, find the salary of Henry.

The graph below shows the production of cycles (in thousands) of two factories (A and B) for ten years. Find the production of cycles of A in the year when combined production of cycles was maximum.

Nhung picks a three digit number and subtract it from the same number after reversing order of its digits. This difference will always be fully divisible by which of following number?

Hiep is brother of Tugleo. Quynh is sister of Hiep. Thanh is brother of Kim. Kim is daughter of Tugleo. Stormy is father of Quynh. Who is the uncle of Thanh?