One person can do a certain job in twenty-one minutes, and another person can do the same job in twenty-eight minutes. how many minutes will it take them to do the job together?

6 min
12 min
24 min

Find the greatest common factor of -30x 4 yz 3 and 75x 4 z 2.

50 points~ ! i have to turn this in tomarrow

Let u = {q, r, s, t, u, v, w, x, y, z} a = {q, s, u, w, y} b = {q, s, y, z} c = {v, w, x, y, z}. list the elements in the set. a ∩ (b ∪ c)a) {q, s, w, y}b) {q, y, z}c) {q, s, u, w, y, z}d) {q, r, w, y, z}