Kayla is working two summer jobs, making $10 per hour lifeguarding and $21 per
hour tutoring. Last week Kayla worked 4 times as many hours tutoring as she worked
lifeguarding and earned a total of $188. Write a system of equations that could be
used to determine the number of hours Kayla worked lifeguarding last week and the
number of hours she worked tutoring last week. Define the variables that you use to
write the system.