A graph showing the monthly cost of an electricity bill for December using the energy companyName: Date:

**ADF Energy**is shown above. The monthly cost of an electricity bill using a different energy company

**Gold Star Electric**is calculated as follows:

**Total Cost (£) = Fixed Monthly Charge of £6.00 + £0.14 x Units of energy used**

1) Draw a graph showing the total monthly cost using the energy company

**Gold Star Electric**

2) Write down the Fixed Monthly Charge of

**ADF Energy**in pounds

3) Calculate the cost per unit of energy used for

**ADF Energy**, in pounds, up to 150 units of energy

4) What would be the total monthly cost with

**ADF Energy**if 250 units were used?

5) If the total monthly cost with

**Gold Star Electric**is £41.00, how many units of energy were used?

6) Compare the total monthly cost of the two energy companies for different energy usages.

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3) The cost per unit of energy for

4) The total monthly cost of using 250 units with

5) 250 units of energy were used.

6)

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2) The Fixed Charge of**ADF Energy**= £18.00

3) The cost per unit of energy for

**ADF Energy**= £0.04 , if up to 150 units of energy are used.

4) The total monthly cost of using 250 units with

**ADF Energy**= £58.00

5) 250 units of energy were used.

6)

**Gold Star Electric**is cheaper when less than 120 or more than 165 units of energy are used. They cost the same when exactly 120 or 165 units of energy are used.

**ADF Energy**is cheaper in between 120 and 165 units of energy.

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