Problema Solution

the sun of the digits of a certain two digit number is 9. when you reverse its digits yo7 increase the number by 9 what is the number

Answer provided by our tutors

let


the digits of the number be x and y

the number is 10x + y

if we reverse the digits we get the number 10y + x


the sum of the digits of a certain two digit number is 9


x + y = 9


when you reverse its digits you increase the number by 9


10y + x = 9 + 10x + y


by solving the system of equations


x + y = 9

10y + x = 9 + 10x + y


we find


x = 4


y = 5


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the number is 45.