10
9
6 of them
You just think of the triangular prism as open. How are you going to fold it to make one? It's actually really easy, I thought it was gonna be hard too!! Luv you guys bye
3 for the top, three for the bottom a one each for connecting the vertexes make 9.
12 straws
<X X> It should look kinda like the example above. Except it would be squares lol. Make two crosses with the 4 long straws put the ends of these together so that one square is made then make two right angles with the four short straws and place them at the other side of each cross to make three squares in a diagonal line. :)
9
6 of them
You need nine sides, so nine straws. But you could just use one straw and cut it into nine pieces.
18 straws.
15 straws are needed
Google 'triangular prism net' and there will be some guides on there.
8
8
You'll need 18 straws because it has 18 edges
15
6
24