Question

[Vương Thiên Di]

Problem 1. Find two distinct numbers, given that their sum is three times their difference, and their product is eight times their difference.

Problem 2. The following sequence of numbers was written on a board: 1, 2, 3, 4, ..., 200. Uyen erased three consecutive numbers and the sum of the remaining numbers is 19848. Find the three numbers that were erased.

Problem 3. The price of a type of chalk in August dropped by 10% compared to that in June, but increased by 10% in October compared to that in August. How many percent has the price increased or decreased from June to October ?

Problem 4.Find the smallest whole number such that when it is multiplied by 12345679, the resulting product is a number having all of its digits equal to 8.

Problem5. Find the digits a and b such that the number  2016ab is divisible by 2 and 9, and has a remainder of 3 when divided by 5.