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 each machine run to produce an order of at least 2080 bolts and 1520 nuts at the minimum operating cost?