Two cars are travelling from Toronto to Quebec. Car A left Toronto at 8 a. m. and is moving with an average speed of 70 km/h. Car B left Toronto at 10 a. m. and its average speed is 90 km/h. How many hours will it take for car B to catch car A? (please show all your work Let, So, Equation and Solution and Therefore Statement)

It'll take 7 hours for the car B to cath up to A

Step-by-step explanation:

In order to solve this problem we can write the equation from the distance of each car. Assuming that t = 0 happens when the second car leaves Toronto. When the second car leaves Toronto, the first one is on the road for two hours already, thefeore it travelled a total of:

distance = speed*time = 70*2 = 140

We have:

Car A:

x(t) = 70*t + 140

Car B:

x(t) = 90*t

We now need to find the value of "t" that makes x(t) the same for both cars:

90*t = 70*t + 140

20*t = 140

t = 140 / 20 = 7 h

the answer to the question is a  

it has the same slope and the same y-intercept.