4 is when you take turn and river , like he has to pay 33% of the pot and he is all in... that means he doesnt pay another bet on the turn, that gives him 36% to get the flush (4*9=36%)

2 is when he pays 33% pot to see the turn(he is not all in), 9*2=18% chance to get flush.... he doesnt get the flush, he will again on the turn same math... so its -