Absolutely correct EC DKN.
Of course, there will be a mathematical formula which can convert a CAS to a TAS but this type of question can be calculated simply and quickly using either a manual flight computer such as the CRP-5 or an electronic flight computer, the latter of which are permitted by some aviation authorities, e.g. FAA, but not by EASA.
I will expand your answer slightly:
1. Refer to the CRP-5's AIRSPEED window.
2. Set the Pressure Altitude of 9,000' on the scale inside the window against the Outside Air Temperature of -5 degrees on the scale outside the window.
3. Look up 17 (170 kts CAS) on the CRP-5 inner scale
4. Read the TAS of 194 kts on the CRP-5 outer scale.
(*I don't have a CRP-5 to hand - unforgivable!!
- but I have 100% confidence in EC DKN's answer
)
I hope this helps.
