Note that winning in the third game, you got at least \$3. So, the outcomes you're interested in are
1. victory in the third game: $0.7$,
2. loss in the third game, but victory in the first two: $0.1 \cdot 0.4 \cdot (1-0.7)$.
Your answer is the sum of the two cases, i.e. $0.712$.