Swan does some work during school holidays. In one week, he spends x hours cleaning cars and y hours repairing cycles. The time he spends repairing cycles is at least equal to the time he spends cleaning cars.
He spends no more than 12 hours working.
He spends at least 4 hours cleaning cars.
a)      Write down 3 inequalities in x and y to show the information.
b)      Draw x and y axes from 0 to 12 using a scale of 1 cm to represent 1 unit on each axis.
c)       Draw 3 lines to show the inequalities and shade the unwanted region.
d)      Swan receives $3 each hour for cleaning cars and $1.50 each for repairing cycles. What is the largest amount he could receive?                                           
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