Question 551133
The value of a certain two digit number is 2 times the sum of it's digits.
 If the digits are reversed, the resulting number is 4.5 times the original number.
:
Let a = the 10's digit
Let b = the units digit
then 10a + b = the original number
:
"the value of a two digit number is 2 times the sum of it's digits."
10a + b = 2(a + b)
10a + b = 2a + 2b
10a - 2a = 2b - b
8a = b
Pretty obvious, the only value that a can be is 1, to give a single digit value for b
18 is the original number
:
"If the digits are reversed, the resulting number is 4.5 times the original number."
81 = 4.5(18)
81 = 81