First we multiply 7 and 0.15 to see how many he lost. We get 1.50 so now we know he lost 1.50 of his collection. we add 5.55 and 1.50 and get 7.05 we divide 7.05 by 0.15 47.
For example, if the function h(n) gives the number of person-hours it takes to assemble n engines in a factory, then the positive integers would be an appropriate domain for the function.