Write a system of equations to describe the situation below, solve using substitution, and fill in the blanks. The student council at Booneville High School is making T-shirts to sell for a fundraiser, at a price of $11 apiece. The costs, meanwhile, are $10 per shirt, plus a setup fee of $129. Selling a certain number of shirts will allow the student council to cover their costs. What will the costs be? How many shirts must be sold?