SOLUTION: The sum of the digits of a 2-digit number is 8.The number obtained by interchanging the digits exceeds the given number by 18. Find the given number

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Question 700041: The sum of the digits of a 2-digit number is 8.The number obtained by interchanging the digits exceeds the given number by 18. Find the given number
Answer by Stitch(470) About Me  (Show Source):
You can put this solution on YOUR website!
The set up is tricky for this problem.
Let A equal one of the numbers
Let B equal one of the numbers
A & B are one digit numbers so they are positive but less than 10
Equation 1: A+%2B+B+=+8
Equation 2:10A+%2B+B+%2B+18+=+A+%2B+10B%29
The numbers are multiplied by 10 to put them in the tens place.
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Solve equation 1 for one of the variables
Equation 1: A+%2B+B+=+8
A+=+8+-+B
Now plug (8 - B) into equation 2 for A
Equation 2:10A+%2B+B+%2B+18+=+A+%2B+10B%29
10%2A%288+-+B%29+%2B+B+%2B+18+=+%288+-+B%29+%2B+10B
Simplify
80+-+10B+%2B+B+%2B+18+=+8+-+B+%2B+10B
Combine like terms
98+-+9B+=+8+%2B+9B
Add 9B to both sides
98+=+8+%2B+18B
Subtract 8 from both sides
90+=+18B
Divide both sides by 18
highlight%285+=+B%29
Now go back and use 5 for B and solve for A.
A+=+8+-+B
A+=+8+-+%285%29
highlight_green%28A+=+3%29