Question 166465
Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r

Let r=rate (speed) of the car
Then r+10=rate of the train

Time travelling by car=120/r
Time travelling by train=150/(r+10) 
Now we are told that the above two times are equal. so:
120/r=150/(r+10)  multiply each term by r(r+10) (or cross multiply)
120(r+10)=150r  get rid of parens (distributive law)
120r+1200=150r  subtract 120r from each side
120r-120r+1200=150r-120r  collect like terms
30r=1200 divide each side by 30
r=40 mph----------------------------speed of the car
r+10=40+10=50 mph--------------------speed of the train

CK
120/40=150/50
3=3

Hope this helps---ptaylor