Hey there!
For Part A, all you need to do is write out an equation for how many dollars Andrew would make for x hours during regular hours (not overtime). Since he makes 6 dollars per hour, this will be 6x.
W = 6x
For Part B, create a similar equation for overtime hours. Overtime hours only apply after Andrew has worked 40 hours, so plug that into your first equation and add that to the second equation.
W = 6x
W = 6(40)
W = 240
S = 240 + 9y
For Part C, consider what we now know. If Andrew earns any money over 240 dollars (which is how much he earns after 40 hours), we know he worked overtime. So, we can just plug 330 into the second equation for S and solve for the number of additional hours he worked, y.
330 = 240 + 9y
– 240 – 240
90 = 9y
9 9
10 = y
Now, we can add up the initial 40 hours plus the additional 10 hours, which is 50 hours total.
Hope this helped you out! :-)