Answer:
So you can either buy all roses or all carnations, or spend $30 on each kind:
12 roses
10 carnations
6 roses & 5 carnations
Explanation:
If you buy a combination of roses and carnations, the amount of money you spend on each has to be a multiple of both 5 and 6. Since these are relatively prime, their least common is 5(6) = 30.
note: the reason it has to be a common multiple of 5 and 6 is because the total amount - 60 - is a common multiple.