We start by listing the outcome of flipping two coins. The first table shows the outcomes HH, HT, TH, and TT. These outcomes then become the input combined with the third coins, as shown in the second table.
We have 8 outcomes in total: HHH, HHT, HHT, TTH, HHT, HTT, TTH, and TTT
The probability that we obtain more tails than heads is 4/8