Digits sum

A two digit number is 3 times the sum of its digits. If 45 is added to the number, its digits are interchanged. Find the sum of the digits of the number.

Correct answer:

s =  9

Step-by-step explanation:

n=ab n=3 (a+b) n+45=ba = 10b+a  10a+b=3 (a+b) (10a+b)+45=10b+a  10 a+b=3 (a+b) (10 a+b)+45=10 b+a  7a2b=0 9a9b=45  Pivot:Row1Row2 9a9b=45 7a2b=0  Row297 Row1Row2 9a9b=45 5b=35  b=535=7 a=945+9b=945+9 7=2  a=2 b=7  n=10 a+b=10 2+7=27  s=a+b=2+7=9



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