Question 66941
Two cargo trains leave the train depot at the same time and are going in the same direction. One travels at 60 miles per hour, and the other travels at 45 miles per hour. Which system of equations could you use to find how long it will take for the trains to be 75 miles apart? \

Let t= time it takes for the trains to be 75 mi apart

For the 60 mph train: d1=60t

For the 45 mph train d2=45t

d1-d2=75 mi

60t-45t=75
15t=75
t=5 hours

AND THE ANSWER ABOVE IS B; SUBSTITUTE d=45t INTO THE OTHER EQUATION: 


ck

In 5 hours the 60 mph train has travelled 300 mi

In 5 hours the 45 mph train has travelled 225 mi

300-225=75 mi


Hope this helps------ptaylor