Yes you balanced it correctly : CH₃CH₂CH₃ ₍g₎ + 5O₂ ₍g₎ -------> 3CO₂ ₍g₎ + 4H₂O ₍g₎
A hack to checking if its correct when they give you the structural formula of one of the species (CH₃CH₂CH₃) is to convert it to the molecular formula and if you get the same answer then it's correct.
So CH₃CH₂CH₃ is the struct-formula for the molec-formula C₃H₈
C₃H₈ + 5O₂ --------> 3 CO₂ + 4H₂O (which means your correct =D)
