Answer: 28x + 15y = 131 and x + y = 7 where x is the number of Dress shirt and y is the number of T-shirt.
Explanation:
We will represent the number of Dress shirt he bought by x and we will represent the number of T-shirt he bought by y.
We know that he spent 131 so the cost of each dress shirt plus the cost of each T-shirt has to equal 131. Also, he bought 7 total shirts so x plus y has to equal 7.
28x + 15y = 131
x + y = 7
Note: it says don't solve so I didn't solve but if you want to solve use these equations.