Answer:
(a) 
(b)
Step-by-step explanation:
The speed of one car is 'S'. The speed of the other car is (S + 10).
In 5 hours, the first car travels (5S) miles, and the other car travels 5(S + 10) miles.
Since they're going in opposite directions, the distance between them at any time
is the sum of the distance that each one has traveled.
500 = (5S) + 5(S + 10)
500 = 5S + 5S + 50
500 = 10S + 50
Subtract 50 from each side:
450 = 10S
Divide each side by 10
S = <u>45</u>
S + 10 = <u>55</u>
I'm not sure which numbers you are referring to, but 3 has the same absolute value as -3, and 7 has the same absolute value as -7, just for an example.