You would have 66 donuts.
If each you have 9900g of donuts and each donut has a mass of 150g, we can divide 9900 by 150 to figure out how many donuts we have. To do this, we first have to figure out how many times 150 goes into 990. It goes into 6 times and has a remainder of 90. Now we have to figure out how many times 150 goes into 900. It goes in 6 times, meaning that our answer is 66 donuts.
1.0 mole of gas at STP occupies 22.4 Litres.
4/0L / 22.4 L/mole = 0.179 moles He.
