Please help mex

Ajar contains a mixture of 20 black marbles, 16 red marbles, and 4 white marbles, all the same size. find the probability of drawing a white or red marble on the first draw. 125 12 01 next question ask for turn it in

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Louis wants to carpet the rectangular floor of his basement.the basement has an area of 864 square feet.the width of the basement is 2/3 it's length. what is the length of louis's basement