The cost to run Machine 1 for an hour is $2. During that hour, Machine 1 produces 240 bolts and 100 nuts. The cost
to run Machine 2 for an hour is $2.40. During that hour,
Machine 2 produces 160 bolts and 160 nuts. With a combined
running time of no more than 30 hours, how long should
each machine run to produce an order of at least 2080 bolts
and 1520 nuts at the minimum operating cost?

this is applications of linear programming