Answer:
Part A: <em>1 hour and 45 minutes.</em>
<em> </em>Part B: <em>10:10 P.M.</em>
Step-by-step explanation:
Part A
We know that 1 hour has 60 minutes.
Then from 7:00 P.M to 8:00 P.M there are 60 minutes.
If 7:35 P.M. is 7 hours and 35 minutes, then the amount of minutes left for 8:00 P.M. is:

From 8:00 P.M. to 9:00 P.M there is 1 hour.
And from 9:00 P.M to 9:20 P.M. there are 20 minutes.
Then you have 1 hour and:

<em>Therefore, How long was the movie?</em>
<em> 1 hour and 45 minutes.</em>
<em> </em>Part B
Knowing that Ushma got home 50 minutes after the movie ended, you need to add 50 minutes to 9:20 P.M:
The amount of minutes left to 10:00 P.M. is:

So, here we have 40 minutes of the 50 minutes she took to got home.
The remaining minutes were:

Then, when 40 minutes passed, the time was 10:00 P.M.
And when you add 10 minutes to 10:00 P.M., you get the time: 10:10 P.M.
Therefore:
<em>Ushma got home at 10:10 P.M.</em>