Question 186851
"the sum of the digits of a two-digit number is 9" ----> t+u=9 ----> t=9-u


" 45 is subtracted from the number, the digits of the number are reversed" 10t+u-45=10u+t



10t+u-45=10u+t


10(9-u)+u-45=10u+9-u


90-10u+u-45=10u+9-u


45-9u=9u+9


45-9=9u+9u


36=18u


u=2


t=9-u


t=9-2


t=7


Original Number: 72