Write a system of equations to describe the situation below, solve using any method, and fill in the blanks.
Janet, an office manager, needs to find a courier to deliver a package. The first courier she is considering charges a fee of $18 plus $1 per pound. The second charges $8 plus $2 per pound. Janet determines that, given her package's weight, the two courier services are equivalent in terms of cost. What is the weight? How much will it cost?
At a package weight of ___ pounds, the two couriers both cost $___.