Fast Food Terminals II

Taco Casa is considering installing touch screen terminals for patrons to place their food orders. A terminal can typically accommodate the placement of $15$ orders each hour while a human can process $20$ orders each hour. If employee costs are $$\frac{7\mathrm{.}50}{?}$ hour in wages and $$4\mathrm{.}50$ hour in taxes, benefits and insurance, what is the per order opportunity cost of a touch screen?