A feed company wants each feed bag that they produce to contain a minimum of 120 units of protein and 80 units of calcium. Corn contains 10 units of protein and 5 units of calcium per pound, and bone-meal contains 2 units of protein and 5 units of calcium per pound. If corn costs 8 cents per pound and bone-meal costs 4 cents per pound, how much of each should they put in each bag, in order to minimize costs?

[math]\mbox{minimize} \; 8c+4t \\ \mbox{such that} \left\{ \begin{aligned} 10c+2b&\geq 120\\ 5c+5b&\geq 80 \\ c,b\geq 0 \end{aligned}\right.[/math]