Volume of Prisms and Cylinders Question Help?

https://snag.gy/HblaES.jpg

https://snag.gy/6i7LzB.jpg

There are 2 questions on each picture. Please, could you explain how to do it?

For the first one, notice that this is just a quarter of a cylinder of radius 15 and height 30. So just find the quarter of the full volume.

For the second, it is again like a cylinder, but the height is 25 and there is a smaller cylinder 'cut out' in the middle. The radius of the smaller cylinder is 3. You need to work out the volume of the overall cylinder and subtract the volume of the smaller cylinder.

For the third, it is best if you split it into 4 identical right-angled triangular prisms, which lengths 4.2, 1.85, and 5.5. Work out the volume of a single one using these measurements then just multiply it by 4 to make up for the other 3.

For the final one, again, you can split it up along the dashed line. Work out the two individual volumes and add them together.