Creeps Attack TD

Hey everyone! Am from Canada, I recently installed a new game from the App Store, Creeps Attack TD - Alien Assault. I love tower defense games so I try all of them which are free.

Can anyone please help me in clearing the level 7 of creeps attack? I don't know which cannon is appropriate for the enemies in that level!

Thanks, hope to get an answer soon!

I am good at them

I love playing games, but am stuck at this one. I bet they made it really hard, can you or someone please try playing it and help me out! Would really appreciate all your help!

Thanks.