SOLUTION: The sum of two digits of a certain two-digit number is 15. If the digits are reversed, the number formed is nine less than the original number. What is the original number?

Algebra ->  Graphs -> SOLUTION: The sum of two digits of a certain two-digit number is 15. If the digits are reversed, the number formed is nine less than the original number. What is the original number?      Log On


   

Question 1046928: The sum of two digits of a certain two-digit number is 15. If the digits are reversed, the number formed is nine less than the original number. What is the original number?
Answer by advanced_Learner(501) About Me  (Show Source):
You can put this solution on YOUR website!
by guess work
87
because
87=78+9
and 8+7=15
by equations
you have
10y+x original number

x+y=15
10x+y=-9+10y+x
9x-9y=-9
x-y=-1
x+y=15
2x=14
x=7
and y=15-7,y=8}