Let's get started !
a. When you go on a treck in the bush, you need to be properly equipped.
==> When going on a treck in the bush, you need to be properly equipped.
b. Campers should clean up the campsite before they leave.
==> Campers should clean up the campite before leaving.
c. Before you light a fire, you should check the signs.
==> Before lighting a fire, you should check the signs.
Hope this helps !
Dreamus