Question 157162

Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r

Let t= time it takes for them to get 100 km apart

During this time, Mr. Anders travels 100t km
And Ms Rich travels 80t km

And we are told that the sum of the above distances equals 100km, So:

100t+80t=100 km
180t=100 km
t=5/9 hr

CK
(5/9)*100+(5/9)*80=100 multiplpy each term by 9
500+400=900
900=900

Another way to look at this problem is to recognize that they are separating at the rate of 100+80 or 180 km/hr

Hope this helps---ptaylor