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The sum of two numbers is 11, and their difference is 9. What are the two numbers?

User Myrcutio
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1 Answer

3 votes

Answer:

10 and 1

Explanation:

Let x and y represent the two numbers. The problem statement lets us write two equations describing their relationships:

x + y = 11

x - y = 9

Adding these equations together, we have ...

(x +y) +(x -y) = (11) +(9)

2x = 20

x = 10 . . . . . . . . . you will notice this is the average of the two given numbers

Then ...

10 + y = 11 . . . . substitute for x in the first equation

y = 1 . . . . . . . subtract 10

The two numbers are 10 and 1.

User Theglauber
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