You can put this solution on YOUR website! You got the equation wrong.
The qustion says one number is 5 more than the other
which can be writen as x + 5 (and not 5x which means 5 times the other number) where x is the first number
now it's pretty easy to solve
x+ x+ 5 =285
2x = 280
and x+5 =145
numbers are 140 and 145