math
posted by MB on .
two trains start from towns 208 miles apart and travel towards each other on parallel tracks. They pass each other 1.6 hours later. If one travels 10 mph faster than the other find the speed of each train?

Sum of speeds = 208 miles/1.6hr=130 mph
Difference of speeds = 10 mph
Faster train = (sum+difference)/2 mph
Slower train = (sumdifference)/2 mph
Explanation:
let f=faster train, s=slower train
S=sum, D=difference, then
S=f+s
D=fs
Add:
(S+D)=f+s+fs=2f
therefore f=(S+D)/2
Simlarly, by subtracting,
SD = f+s  (fs) = 2s
therefore s=(SD)/2