Given Data:
The salery of Jonny per hour is: $15
The bonus received at the end of month is: $85
The amount made by Jonny at the end of month is: $685
Let 'x' represents the number of hours Jonny worked in a month.
The expression to calculate the amount earned by Jonny at the end of month is,
Here, 'S' represent the total monut earned by Jonny in a month.
Substitute S=$685, and solve for 'x' to calculate the total hour worked by Jonny.