Using a formula I

This task is about working out what parts of a formula mean.
The Grandstand Rugby Clothing Company sells their products over the Internet.

Question

a)
They use this formula to work out how much it costs in total to buy and transport jerseys within New Zealand.
 
 
C = 100x + 5
 
What does the x in the equation represent?
 

    • The total cost of the jerseys.

    • The number of jerseys ordered.

    • The cost of transportation.

    • The cost of each jersey.

How did you work this out?

Question

b)
They use the following formula to work out the total cost of exporting an order of scarves to England.
 
 
          C = 40z + 15
 
What does the 15 in the equation represent?

    • The number of scarves ordered.

    • The cost of each scarf.

    • The total cost of the scarves.

    • The cost of transportation.

How did you work this out?