I think you are supposed to make the fraction equivalent so you know that 27/9 is 3, so you would do the same thing whatever number is supossed to be under 17 needs to equal to 2 when divided by 9. So you should probably know that 3 * 9 is 18 so x needs to be a number that when subtracted by 5 gives you 18. So x=23. Hope this is right and it helps!