Mila spent 4 hours at baby sitting and 6 hours at life guarding
<em><u>Solution:</u></em>
Given that, Mila is working two summer jobs, making $9 per hour babysitting and $17 per hour life guarding
Amount earned from babysitting = $ 9 per hour
Amount earned from life guarding = $ 17 per hour
Last week Mila earned a total of $138 and worked 2 more hours life guarding than hours babysitting
Let "b" represent the number of hours spent babysitting
Then, the number of hours spend at life guarding is b + 2
Also, total amount earned last week = $ 138
<em><u>Then, we can frame a equation as:</u></em>
Amount earned from babysitting x number of hours spent babysitting + Amount earned from life guarding x number of hours spend at life guarding = 138

<em><u>Then, number of hours spent at life guarding:</u></em>
b + 2 - 4 + 2 = 6 hours
Thus she spent 4 hours at baby sitting and 6 hours at life guarding