Answer:
There are 21 ways to choose the first person, 20 ways to choose the second, 19 ways for the third and 18 ways for the fourth so the answer is 21 * 20 * 19 * 18 = 143640.
y=45+x
y=2x+15
x=30
Step-by-step explanation:
B.
1/2
3/6 = 1/2
