Help me! I dont get this

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps

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.

Roy has 4 1/2 pizzas for the soccer team to split after the game. if each member is going to get 1/2 of a pizza, how many players are on the soccer team