Question 966609
The combined speed of the trains is 920 miles/8 hours=115 mph
a=speed of train a and a+15mph=speed of train b:
a+a+15mph=115 mph Subtract 15 mph from each side.
2a=100 mph Divide each side by 2.
a=50 mph ANSWER 1: The average speed of train a was 50 mph.
a+15mph=50 mph+15 mph=65 mph ANSWER 2: The average speed of train b was 65 mph.