Penny has made a pattern of shapes on her bedroom walls. she drew a rectangle, 2 circles, a rectangle, and then 2 more circles until she drew 24 circles. how many shapes did she draw in all?

For every rectangle she draws she draws 2 circles so 1/2. If she has 24 circles then she is going to have half of that amount but for the rectangles. In other words she has 12 rectangles leading to the fact that she has 36 shapes all together ...