Question 838771
Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r
Let r=car A's rate
Then r+10=car B's rate

Time travelled by car A=120/r
Time travelled by car B=150/(r+10)
Now we are told that these times are the same, soooo:
120/r=150/(r+10) multiply each side by r(r+10)
120(r+10)=150r simplify
120r+1200=150rsubtract 120r from each side
120r-120r+1200=150r-120r
30r=1200
r=40mph---Car A speed
r+10=40+10=50 mph -----Car B's speed (or rate)
CK
120/40=150/50
3=3

Hope this helps--ptaylor