Math please help! thanks !

Please explain! i don't understand thank you so much.(:

Tara and Brian leave a concert at 11:30 pm. They travel in opposite directions. Tara drives 55 miles per hour and Brian drives 45 miles per hour. At what time will they be 150 miles apart?

A. 12:00 a.m.

B. 12:10 a.m.

C. 1:00 a.m.

D. 1:20 a.m.

They are driving apart at 100mph ( 45 + 55)
100 / 60 = 1.66 miles per minute

150 / 1.66 = ~90 minutes until they are 150 miles apart
90 minutes is 1 hour and 30 minutes.

11:30pm + 1:30 = 1:00 am

we presume that they travel X hour
55X + 45X = 150
Then X = 1.5 hour

The answer should be C

In one hr, they will be 100 mi apart.
In 90 min, they will be 150 mi apart.

11:30 pm + 90 min = 1 am

C

c. Their relative speed is 100 mph.