SOLUTION: The sum of the digits of a two-digit counting number is 9. When the digits are reversed, the new number is 45 less than the original number. What is the original number?
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Question 625518: The sum of the digits of a two-digit counting number is 9. When the digits are reversed, the new number is 45 less than the original number. What is the original number? Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website! The sum of the digits of a two-digit counting number is 9. When the digits are reversed, the new number is 45 less than the original number. What is the original number?
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let u=units digit
let t=tens digit
u+t=9
u=9-t
original number: 10t+u
new number: 10u+t
..
10t+u=10u+t-45
10t+9-t=10(9-t)+t-45
10t+9-t=90-10t+t-45
10t+9-t=90-10t+t-45
18t=36
t=2
u=9-t=7
original number:27
new number: 72
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