Let's begin by listing out the information given to us:
Amount earned (old job) = $1,650 /month
New job rate (r) = $9.80 /hour
Time (t) = 36 hours /week
Remember that 1 month = 4 weeks. It means that time in months is equal to:
Time (t) = 36 * 4 = 144 hours /month
Amount earned (new job) = New job rate * Time
Amount earned (new job) = 9.80 * 144 = $1,411.20
Deficit = Amount earned (old job) - Amount earned (new job)
Deficit = 1,650 - 1,411.20 = $238.80
To calculate how many hours overtime, divide the deficit by the job rate
Hours overtime = 238.8 / 9.8 = 24.37 hours / month
Hours overtime = 24.37/4 = 6.09 = 6.1 hours / week
Mark would have to work 6.1 hours overtime per week to earn the same amount per week as his current job
