SOLUTION: The sum of the digits of a 3-digit number 15. If the tens and the units are interchanged, the original number will be 9 more than the new number. If the units and the hundreds digi

Question 456236: The sum of the digits of a 3-digit number 15. If the tens and the units are interchanged, the original number will be 9 more than the new number. If the units and the hundreds digits are interchanged, the new number will be 99 more than the original number. What is the original number?
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Let x= the hundreds digit
and let y=the tens digit
and z=the units digit
Now we are told that x+y+z=15----eq1
We know that the original number is:
100x+10y+z
If the tens and units digits are interchanged, the new number will be:
100x+10z+y
Now we are also told that:
100x+10y+z=100x+10z+y+9 simplify by subtracting 100x+10z+y from each side
100x-100x+10y-y+z-10z=9 collect like terms
9y-9z=9 or
y-z=1-------------------------------eq2
If the units and hundreds digits are interchanged, we have:
100z+10y+x and this number is 99 more than the original number, so:
100z+10y+x=100x+10y+z+99 simplify by subtracting 100x+10y+z from each side
100z-z+10y-10y+x-100x=99
99z-99x=99 or
z-x=1------------------------------eq3
From eq2, y=1+z and from eq3, x=z-1
substitute these values into eq1 for for x and y and we get:
z-1+z+1+z=15
3z=15
z=5
Now from eq2:
y-5=1
y=6
and from eq3
x=5-1=4
So the original number is:
465------------------------------ans
CK
465 is 9 more than 456, and
564 is 99 more than 465
Hop this helps---ptaylor

RELATED QUESTIONS
In a certain three digit number, the hundreds digit is the sum of the other two digits.... (answered by ankor@dixie-net.com)

25. The sum of the tens and hundreds digits of a three-digit number is 12. The units... (answered by ptaylor)

The tens digit is twice the units digit. The sum of the original number and the number... (answered by stanbon)

The units digit is 1 more than 3 times the tens digit in a two digit number. The number... (answered by ankor@dixie-net.com)

The sum of the digits of a three-digit number is 13. If the tens and hundreds digits are... (answered by ankor@dixie-net.com)

The units digit of a number is 4 times the tens digit. If 54 is added to the number, the... (answered by kevwill)

Hi In a 3 digit number the units digit is 3 more than the tens digit and the sum of the... (answered by math_tutor2020,greenestamps)

1) The sum of a 3-digit number is 18. If he second and third digits are interchanged, the (answered by ankor@dixie-net.com)

The tens digit of a three-digit number is 0. The sum of the other digits is 6.... (answered by Alan3354,greenestamps)