The rectangle shown is not shown. Without seeing the rectangle, we don't know what part of it 'x' is. For all we know, we are being scammed, and there is no 'x' in the rectangle at all. Using the information given, no answer is possible.
Take Kitzen's number of raffle tickets and put them over Ava's tickets to give you 12/16 and the simplify which gives you 3/4 because the fraction is divisible by 4.
