Question 741882
Twice the tens digit of a positive, two-digit integer is 1 less than the ones digit. Reversing the digits increases the number by 45. What is the number?
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t = 10's digit
u = units
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2t + 1 = u
10t + u + 45 = 10u + t
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2 eqns in 2 variables
2t + 1 = u --> u = 2t + 1
10t + u + 45 = 10u + t --> 9t + 45 = 9u --> t + 5 = u
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u = 2t + 1
t + 5 = u
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t + 5 = 2t + 1
t = 4
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u = 9
--> 49