Whats the smallest length marked on a centimeter ruler

Determine the relationship of ab and cd given the following points

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?

3c2 + 2d)(–5c2 + d) select all of the partial products for the multiplication problem above.