Answer: John earn $4.95 per hour for the first 40 hours.
Explanation:
Since we have given that
Amount he earned for the first 40 hours that he works that week be 'x'.
Let the amount earned for each additional hour be 'y'.
If John works 45 hours in a week, he earns a total of $570 that week.
According to question, we get that

As we have given that
y=15x.
so, substituting the above value we get that

Hence, John earn $4.95 per hour for the first 40 hours.