Answer:
I can't see the question?!
Step-by-step explanation:
N = 20, r = 15;
n C r = ( n * ( n - 1) ( n - 2 ) ... ( n - r + 1 )) / r ! =
20 C 15 = (20 * 19 * 18 * 17 ......8 * 7 * 6) / (15 * 14 * 13 ...* 5 * 4 * 3 * 2 * 1) =
= 15,504
Answer:
They can choose 15 questions in 15,504 ways.
Answer:
(X,Y)(18,12)
Step-by-step explanation:
x + y = 30
2x + 4y = 84
___________
2x+2y=60
2x+4y=84
_________
-2y=-24/-2y
y=12
2x+4(12)=84
2x+48=84
2x=84-48
2x/2=36/2
X=18
Subtract 14x from both sides to get

Subtract 12 from both sides to get

Now we have moved all terms involving x on one side, and all constant terms on the other. We can simplift both sides, i.e. sum like terms, to get

Now we have to divide both sides by 6. When dealing with inequality you have to be careful about dividing both sides by the same constant: if the constant is negative, the inequality side switches (i.e.
). But this is not the case since 6 is positive, so we mantain the inequality sign:
on the other. We can simplift both sides, i.e. sum like terms, to get

Evaluate left and right hand side:

Answer:
Two times the sum of a number and nine.
Step-by-step explanation: