Chalkboard Math Problem Image Generation

A prompt for Nano Banana Pro to generate an image of a math problem written and solved on a green chalkboard with chalk, aiming for a realistic, imperfect texture (chalk dust, pressure marks) to enhan

Write the given question on a green board with chalk and solve it.
There is a number y. Multiply that number by 3. Add the same number y to it. Then it becomes 6×x.
When x = {argument name="value of x" default="2"}, what is y?