Design avending machine which dispenses a newspaper which is of price Rs$\mathrm{.}15/-$ Consider input as two separate coins Dines $(D)=Rs\mathrm{.}10/-$ and Nickels $(N)=Rs\mathrm{.}5/-.$The machine accepts single coin at a time. If the machine load Rs$\mathrm{.}20/-$ it won't give any balance amount, with it further user has to insert Rs$.10/-$ to dispense another newspaper.