โจทย์คณิตศาสตร์และวิธีทำบนกระดานดำ

A math problem handwritten in white chalk on a classic green chalkboard with chalk dust and varying stroke pressure marks. The problem and step-by-step solution are written neatly: "Question: There is a number y. Multiply that number by 3. Add the same number y to it. Then it becomes 6×x. When x = [2], what is y? Solution: 3y + y = 6x 4y = 6x When x = [2]: 4y = 6(2) = 12 y = 3"