Answer:
The function that gives the price [tex]c[/tex] for a number of rooms [tex]r[/tex] is [tex]c(r) = 160\cdot r[/tex].
Step-by-step explanation:
This problem shows a case of composition between two function, which is defined as follows:
[tex]c(r) = c\,\circ\,h (r) = c(h(r))[/tex] (Eq. 1)
Where:
[tex]c[/tex] - Price, measured in US dollars.
[tex]h[/tex] - Packing time, measured in hours.
[tex]r[/tex] - Number of rooms, dimensionless.
If we know that [tex]c(h) = 40\cdot h[/tex] and [tex]h(r) = 4\cdot r[/tex], then the composite function is:
[tex]c(r) = 40\cdot (4\cdot r)[/tex]
[tex]c(r) = 160\cdot r[/tex] (Eq. 2)
The function that gives the price [tex]c[/tex] for a number of rooms [tex]r[/tex] is [tex]c(r) = 160\cdot r[/tex].