Since the variation is direct, then we have a function of the form:
[tex]c = kn
[/tex]
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:
[tex]54 = k (9)
[/tex]
From here, we clear the value of k:
[tex]k = 54/9
k = 6[/tex]
Therefore, the function is:
[tex]c = 6n
[/tex]
For n = 3 we have:
[tex]c = 6 (3)
c = 18 $[/tex]
Answer:
the cost of the sandwiches when n is 3 is:
c = 18 $
