A plumber charges a price for each hour, £h, and a fixed charge, £c.

A 5 hour job costs £155 in total.

A 8 hour job costs £230 in total.

How much would a job that lasts 2 hours cost?

A 2hr job will cost £80 total

Step-by-step explanation:

Check image below for detailed calculations

A job that lasts 2 hours would cost £80

Step-by-step explanation: The plumber charges a fixed charge c, and an hourly charge h. For a 5-hour job he charged as follows;

c + 5h = 155 (1)

Also for a 2-hour job he charged;

c + 8h = 230 (2)

With the pair of simultaneous equations we can now determine the values of c and h respectively.

c + 5h = 155 (1)

c + 8h = 230 (2)

We shall solve by use of the elimination method. Subtract equation (1) from equation (2)

3h = 75

Divide both sides of the equation by 3

h = 25

We can now substitute for the value of h into equation (1)

c + 5(25) = 155

c + 125 = 155

Subtract 125 from both sides of the equation

c = 30

This means his fixed charge is £30 and his charge per hour is £25.

Therefore for a 2 hour job his total charge would be;

Cost = c + 2h

Cost = 30 + 2(25)

Cost = 30 + 50

Cost = 80

So, a job that lasts two hours would cost £80