At a florist's shop, two assistants made 13 flower arrangements in a certain amount of time. Assuming all assistants will work for the same amount of time and each assistant is trained to work at the same rate, how many assistants are needed to make: 39 arrangements, 91 arrangements, and 195 arrangements.

It will take 6 assistants for 39 arrangements, 14 assistants for 91 arrrangements, and 30 assistants for 195 arrangements. To get this we know that it takes two assistants per 13 arrangements so you just find how many times 13 goes into the number, then multiply by 2.