Question 444638
Let x be the first digit.
Let 15-x be the second digit.
...
10x+(15-x)+9=10(15-x)+x ... the 10's column is worth per digit (10 times).
9x+24=150-10x+x
9x+24=150-9x
9x+9x=150-24
18x=126
x=7
15-x=8
...
Therefore, the number is 78.