A DIESEL TRAIN LEFT THE STATION TEN HOURS BEFORE A FREIGHT T

A DIESEL TRAIN LEFT THE STATION TEN HOURS BEFORE A FREIGHT TRAIN. THE TRAINS TRAVELED IN OPPOSITE DIRECTIONS. THE FREIGHT TRAIN TRAVELED AT 20 mph FOR ONE HOUR. AFTER THIS TIME THE TRAINS WERE 680 MILES APART. FIND THE DIESEL TRAIN\'S SPEED.
I got 22mph for the diesel.
20x + 20(x-10) = 680
Thank you in advance for your help.

Solution

Let\'s check your answer:
The diesel travelled 11 hours at 22 mph or 242 mi; the freight train travelled 1 hour at 20 mph or 20 mi; 242 + 20 does not add up to 680 Mi
If you laid out these word problems so we know what x stands for, it would
usually make the problem easier
Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r
Let r=rate of the diesel train
Total distance diesel train travelled=r*10 or 10r+r*1=11r
Total distance freight train travelled =20*1=20 mi
Ande we are told that the above two distances add up to 680 mi, so:
11r+20=680 subtract 20 from both sides
11r=660 divide each side by 11
r=60 mph-------------------rate of the diesel

Hope this helps