Let the three numbers be a, b, and c, where c is the greatest number.
Step 1: Translate Jonah's actions into a fraction
The average of the other two numbers is: (a + b) / 2
Jonah adds the greatest number (c) to that: c + (a + b) / 2
He divides everything by 2: (c + (a + b) / 2) / 2
To clean up this double fraction, we multiply the top and bottom by 2:
Jonah's Final Number = (2c + a + b) / 4
Step 2: Compare it to the true average
The true average of all three numbers is: (a + b + c) / 3
The problem says Jonah's number is "x more than" the true average:
(2c + a + b) / 4 = (a + b + c) / 3 + x
Step 3: Clear the fractions
Multiply every single term by 12 to get rid of the denominators:
3 * (2c + a + b) = 4 * (a + b + c) + 12 * x
6c + 3a + 3b = 4a + 4b + 4c + 12x
Step 4: Group the letters together
Move all the a, b, and c terms to the left side by subtracting them:
(6c - 4c) + (3a - 4a) + (3b - 4b) = 12x
2c - a - b = 12x
Step 5: Find the final answer
The question asks for the difference between the greatest number (c) and the average of the other two ((a + b) / 2):
Difference = c - (a + b) / 2
To combine these into one fraction, give c a common denominator:
Difference = (2c - a - b) / 2
Since we already discovered in Step 4 that (2c - a - b) equals 12x, we substitute it right into the formula:
Difference = 12x / 2
Difference = 6x
Correct Answer: E. 6x