Let's say that the time it took him to get to work in the morning is t hours. Then the time it took him to get home in the afternoon must be 1 - t hours. We know that for any trip, distance equals rate times time or d = rt . That means that the distance he drove to work is given by , but we also know that the distance he drove to get home must be the same distance, because he took the same route (and, presumably, no one picked up him house and moved it while he was at work) so for the trip home we can say d = 30 × (1 - t) and since the distances are equal, we can say:
The angles diagonally opposite each other are congruent while those adjacent to each other add up to 180 degrees. You can get eight congruent angles with a transversal if the two lines are parallel, because each angle would be 90.