Identify two changes to personal information which you must report to your employer.

First is Marriage, when you are married you must report to your employer to provide necessary changes in you information especially if you are a woman where your last name will be changed. Second is the Contact Details. When there is a change in your contact information you must report it immediately to your employer for urgent concerns when they need to call you. 

Trevor's earning per hour is $7.80. Since he works for 20 hours each week, his earning each week is given by $7.80 x 20 = $156 per week. Trevor wants to bu a laptop costing $780, to obtain the number of weeks it takes Trevor to achiev his goal of buying the laptop, we divide the cost of the laptop by his earnings per week. Therefore, it will take Trevor $780 / $156 = 5 weeks to achieve his goal.