Posted by Joe Mhar Plaza on .
The sum of the of a twodigit number is 15. One third of the number diminished by 12 is 17. Find the number.

Exploring mathematics elementary algebra 
Reiny,
Did you mean the "sum of the digits of a twodigit number is 15" ?
if so, then
let the unit digit be x
let the tens digit be y
so the value is 10y + x
"One third of the number diminished by 12 is 17"
> (1/3)(10y+x)  12 = 17
(1/3)(10y+x) = 29
multiply by 3
10y+x = 87
x = 87  10y
also x+y = 15
by substitution:
8710y + y = 15
9y = 72
y = 8
x = 87  80 = 7
the number is 87
check the properties stated.