The sum of the digits of a certain two-digit number is 8. When you reverse its digits you decrease the number by 72. What is the number?

Question

Calculus question - word problem!

Answer 1

It is 80    

 

80 - 08 = 80 - 8 = 72

 

 80         =  8 + 72

 

10*8 +  0 =  10*0 + 8 + 72

10  T +  O = 10*O  +T + 72

 

10 T + (8-T) = 10(8-T) + T + 72

 

10 T + 8 - T = 80 - 10T + T + 72

 

9T + 8 = 152 - 9T

 

18T + 8 = 152

 

18 T = 144

 

T = 8

 

Then O = 8 - T  = 8-8 = 0