Question

The cost, c, of a ham sandwich at a deli varies directly with the number of sandwiches, n. If c=$54 when n is 9, what is the cost of the sandwiches when n is 3

Answer 1

Since the variation is direct, then we have a function of the form:

`c = kn`
From here, we must find the value of the constant k.
For this, we use the following data:
c = $ 54 when n is 9
Substituting values we have:

`54 = k (9)`
From here, we clear the value of k:

`k = 54/9 k = 6`
Therefore, the function is:

`c = 6n`
For n = 3 we have:

`c = 6 (3) c = 18 $`
Answer:
the cost of the sandwiches when n is 3 is:
c = 18 $