#3 is a triangular pyramid because triangular pyramids have 4 triangular faces.
#4 is a cube because there are 6 square faces.
#5 is a triangular prism. It has 2 triangular faces and 3 rectangular faces.
#6 is a rectangular prism. It has 2 square faces and 4 rectangular faces.
(If you don't know what the figure of the net is, resketch it on another piece of paper, cut it out, and form it.)
Hope this helps,
Loafly
The first space is for the slope, which would be 2. The second is for the y-intercept, which is 110.
So if you fill those in, it would be N=2M+110
