A train travels due east at a velocity of 85.5 km/hr. A passenger walks from the front of the train to the back at a velocity of 3.7 km/hr. What is the velocity of the passenger to an observer who is seated on a train going due west at a velocity of 64.7 km/hr?

What I've done so far:

I found the total distance east of the passenger on train one, which I think is 85.5-3.7, so the passenger on train 1 is going 81.8 km/hr.

I think the final step is to add this distance (81.8) to the other train's distance (64.7) to find the relative velocity. Adding these together gave me 1.5 * 10^2 (significant figures). Is this the proper way to go about this answer?

yes. But it's probably better just to say 146.5 km/hr

the numbers are not so big as to need scientific notation, and they were all defined with one decimal place of accuracy.

To calculate the velocity of the passenger with respect to an observer on the second train, you need to consider the relative velocities.

The velocity of the first train going east is 85.5 km/hr. This is positive because it is heading in the positive direction.
The velocity of the passenger walking from the front to the back of the train is 3.7 km/hr. This is also positive because it is in the same direction as the first train.

To calculate the total velocity of the passenger with respect to an observer on the second train, you need to subtract the velocity of the second train going west from the total velocity of the passenger on the first train.

Here's how you can calculate it:

1. Calculate the velocity of the passenger with respect to the observer on the first train:
Velocity of the passenger on train 1 = 85.5 km/hr - 3.7 km/hr = 81.8 km/hr

2. Calculate the velocity of the passenger with respect to the observer on the second train:
Velocity of the passenger with respect to observer on train 2 = 81.8 km/hr - (-64.7 km/hr)
= 81.8 km/hr + 64.7 km/hr
= 146.5 km/hr

So, the velocity of the passenger with respect to an observer on the second train is 146.5 km/hr.