Which is a multiple of 15?

The multiples of 15 are the numbers which are n-times of 15, where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and so on. So, basically, multiples are n-times of any number, where n is the list of natural numbers. Thus, number 15 has multiples in the form of 15n, such that: 15 x 1 = 15

the ratio of balloons to tables is 5: 2 and the constant variation is 5.

the equation is y=5x