Answer:
Step-by-step explanation:
To make this easier we are going to make a table and fill it in with the pertinent information. That's the first step; the second one is figuring out how to use the information in the table to come to some sort of a viable and reasonable (and hopefully correct) answer. The table will look like this:
d = r * t
Car 1
Car 2
What we know first off is that the time in question, the IMPORTANT time is 9 hours. That they left at the same time doesn't give us any numbers to put into our table or any useful information. We are looking at what happens at 9 hours. So that's what goes into the t column:
d = r * t
Car 1 9
Car 2 9
What we are then told is that after this 9 hours they are a certain distance apart. We'll come back to that. One car is traveling 10 km/h slower than the other, but since we don't know what the rate of the other car is either, they are both unknown. And it just so happens that this the information we are asked to solve for.
d = r * t
Car 1 r * 9
Car 2 r - 10 * 9
Now, since d = rt, we multiply the rate times the time and fill in the distance each has gone in 9 hours:
d = r * t
Car 1 9r = r * 9
Car 2 9r - 90 = r - 10 * 9
The distance between these 2 cars after that 9 hours is 910 km, therefore:
distance that car 1 traveled + distance that car 2 traveled = 910 km:
9r + 9r - 90 = 910 and
18r - 90 = 910 and
18r = 1000 so
r = 55.56 km/hr
and the other car is going 10 km/hr slower at 45.56 km/hr
