Write a system of equations to describe the situation below, solve using any method, and fill in the blanks. Cody, an office manager, needs to find a courier to deliver a package. The first courier he is considering charges a fee of $15 plus $3 per pound. The second charges $5 plus $4 per pound. Cody determines that, given his package's weight, the two courier services are equivalent in terms of cost. How much will it cost? What is the weight?