Let the first number be 'x' and the second number is 'y'
Equation 1: x + y = 52
Equation 2: x - y = 38
Rearranging equation 2 to make either x or y the subject
x = 38 + y
Substituting x = 38 + y into equation 1
x + y = 52
(38+y) + y = 52
38 + 2y = 52
2y = 52 - 38
2y = 14
y = 7
Substitute y = 7 into either equation 1 or equation 2 to find x
x + y = 52
x + 7 = 52
x = 52 - 7
x = 45
x = 45
y = 7
Answer:
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Answer:
B. 0.602%
Step-by-step explanation:
Probability is essentially (# times specific event will occur) / (# times general event will occur). Here, we have a few specific events: draw a quarter, draw a second quarter, draw a penny, and draw another penny. The general event will just be the number of coins there are to choose from.
The probability that the first draw is a quarter will be 4 / (4 + 8 + 9) = 4/21.
Since we've drawn one now, there's only 21 - 1 = 20 total coins left. The probability of drawing a second quarter is: (4 - 1) / (21 - 1) = 3/20.
The probability of drawing a penny is: 9 / (20 - 1) = 9/19.
The probability of drawing a second penny is: (9 - 1) / (19 - 1) = 8/18.
Multiply these four probabilities together:
(4/21) * (3/20) * (9/19) * (8/18) = 864 / 143640 ≈ 0.602%
The answer is B.
