There are 10 letters in the set {a, b, c, d, e, f, g, h, i, j} which is the pool of letters to choose from when making these three letter codes.
We have 10 choices for slot 1
Then 9 choices for slot 2. This is because we can't reuse the choice for slot 1
Then 8 choices for slot 3
Overall, there are 10*9*8 = 90*8 = 720 different permutations
Answer: 720
Note: you can use the nPr permutation formula with n = 10 and r = 3 to get the same answer
Answer:
210
Step-by-step explanation:
you can do 200 + 10 = 210
You can also do 200 + 1 x10
Answer: Choice A. (8, 4)
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Explanation:
Because x = 2y, we can replace every copy of x with 2y
Let's do so in the second equation
3x - 4y = 8
3(x) - 4y = 8
3(2y) - 4y = 8 .... x replaced with 2y; now let's isolate y
6y - 4y = 8
2y = 8
y = 8/2 ..... divide both sides by 2
y = 4
Use this y value to find x
x = 2y
x = 2*4
x = 8
So we have x = 8 and y = 4 pair together to get the answer (x,y) = (8, 4) which is choice A.
