Checkout ladder #220 climbs from 24 to 117 in five steps — 24, 52, 65, 91 and 117 — with three darts per finish and a double to end on.
24 is a straight double: D12. If the dart lands in the single by mistake you are left on 12, which still has a double finish with the darts you have left. 52 is a two-dart finish: 12 D20.
65 is a two-dart finish: T19 D4. 91 is a two-dart finish: T17 D20. 117 needs all three darts: T19 20 D20. If the first dart misses its treble, the board will show the new route straight away.
At best the five finishes need 10 darts out of 15. Your result counts the finishes you make first and the darts you used second. The middle finishes decide this ladder. Choose the route that leaves a double after a missed treble; the suggested routes do that wherever they can.