Imran runs a successful mobile car wash business. He goes to busy client's homes to wash their cars.  His plan for 2022 was to do 260 car washes charging clients $100 per wash. He has also planned that each car wash takes 2 hours. He uses a team of casual workers and he plans to pays them $20 per hour.  At the end of 2022 Imran goes through his accounting records to evaluate his business and make plans for the next year. He has done 300 car washes and earned total sales revenue of $27,000. He has spent $13,500 on labour costs.  What is the flexible budget variance for the labour costs?