Volume and pressure have an inverse relationship--if you double one of them the other must be halved, if you reduce one of them to a third of its original value, the other must triple in value.

10. The new volume will be half the original value: 50 L

11. The new gas pressure will be quadruple the original value: 20 atm

12. The new volume will be triple the original value: 45 L x 3 = 135 L

13. Temperature and volume have a direct relationship--if you double one of them, the other will also double (presuming we are keeping the pressure constant throughout).

So the new temperature will be 3/2 times the original value: 150 L