Describe the three geometric figures that can result from the intersection
of a plane with a solid, and sketch an
example of each.

His hourly rate is $13.75.

Let x be the hourly rate.  Since he works 20 hours that week, the hourly wages are given by 20x.  We add to that his commission, which is 16% of the $1500 in sales, or 0.16(1500).  This totals to 515:

20x + 0.16(1500) = 515
20x + 240 = 515

Subtract 240 from both sides:
20x + 240 - 240 = 515 - 240
20x = 275

Divide both sides by 20:
20x/20 = 275/20
x = 13.75.