Curtis decided to go on a road trip to Canada. On the first day of his trip, he drove for 10 hours and traveled 640 miles. At what rate did he travel on the first day, in miles per hour?

Factor completely. x^8 - 1/81 a) (x^4 + 1/9)(x^2 + 1/3)(x^2 - 1/3) b) (x^4 - 1/9)(x^2 + 1/3)(x^2 - 1/3) c) (x^4 + 1/9)(x^2 - 1/3)2

Find the value of the variable and the length of each secant segment.

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.