Question

The running costs of a particular factory consist of two components – a constant charge per week for rent of premises and a variable cost for labour which depends on the number of staff working in the factory in that particular week.
The total weekly running costs are $20 000 when there are 25 staff and $35 000 when there are 50 staff working the factory.
Write an equation that describes the relationship between the total cost, C, and the number of staff, n.
Use your equation to calculate the total weekly cost when 35 staff are working the factory.

Answer 1

Look at it as being given 2 ordered pairs
(25,20000) and (50,30000), and being asked to find the equation of the straight line.
Your general point will be (n,C)
slope = (30000-20000)/(50-25) = 400

now you have the slope and using one of the given points, find the equation using the method that was taught to you.

For the last part, sub in n = 35, then find C