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12 votes
A first number plus twice a second number is 23. Twice the first number plus the second totals 22. Find the numbers

User Eric Stdlib
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1 Answer

23 votes
23 votes

Answer:

7 and 8

Explanation:

Let x = the first number

Let y = the second number

First number plus twice a second number is 23: x + 2y = 23

Twice the first number plus the second totals 22: 2x + y = 22

Equation 1: x + 2y = 23

Equation 2: 2x + y = 22

Rewrite equation 1 to make x the subject:

x = 23 - 2y

Substitute into equation 2 and solve for y:

⇒ 2(23 - 2y) + y = 22

⇒ 46 - 4y + y = 22

⇒ -3y = -24

⇒ y = 8

Substitute found value for y into one of the equations and solve for x:

⇒ 2x + 8 = 22

⇒ 2x = 14

⇒ x = 7

Therefore, the two numbers are 7 and 8

User Martin Foot
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