18 straws.
5
15
15 straws are needed
6
8 straws.
You need nine sides, so nine straws. But you could just use one straw and cut it into nine pieces.
15
24
9
six, you need six
6
15 straws are needed
You'll need 18 straws because it has 18 edges
6
6
10
8 straws.
A hexagon and a rectangle.