Please tell me the what to do with this problem

Because the prices are different, you need to use two variables, one for each price.
Let the price for the plain one be X and the price for the printed one be Y.
You would multiply the number of each shirt by the variable:
3 plain would be 3X and 2 printed would be 2Y.
You then need to add those together to get the total cost:
Total cost = 3X + 2Y
Answer:
3x+2y
Step-by-step explanation:
You should first convert the plain and printed t-shirts prices into variables. I called the plain t-shirts price "x" and the printed t-shirts price "y". There are three plain t-shirts, so the price of the plain t-shirts are 3x. There are two printed t-shirts, so the price of them would be 2y. Add them and you'll get 3x+2y