how do i complete and balnces theses reactions????

Question

CH3-CH2-CH3 (g) + Br2 (l) -->

like how in the world????? do i do this?

lol aint got a clue wish i would have listened at school now.

Alkanes usually react with a halogen to form one of several halides. The simplest reaction is to add one atom of Br on the end of the reaction. That is, the end H reacts with one atom of Br to form HBr and the other atom of Br adds to the spot vacated by the H atom.
CH3CH2CH3 + Br2 ==> HBr + CH3CH2CH2Br.
In practice and under various conditions, additional Br atoms may add to the other spots held by H atoms. I hope this helps.