VTMO 2026 - Grade 2 - Semifinal - SET 9 - Self-study Question 17

Đào and Hằng start with the same number of candies. Every day, Đào eats 3 candies and Hằng eats 2 candies. After some days, Đào has 4 candies left and Hằng has 9 candies left. How many candies did each friend have at the start?