When the fundraiser began, 600 people wanted to purchase the dance troupe’s t-shirts at $12 per t-shirt, but as the group increased the price of their t-shirts, they noticed a fall in the demand. for every $1 increase in price, the demand fell by 50 shirts. the dance troupe’s initial supply was short by 210 t-shirts which corresponded to an initial price of $9.75. for every $1 increase in price, they ordered 40 more t-shirts. write a system of linear equations to represent both the demand and supply for the t-shirts. let q represent the quantity of t-shirts and p represent the price.