Igot a, b, d, e. can i have with confirmation?

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

10 ! a train starts from grand city and travels toward belleville 388 miles away. at the same time, a train starts from belleville and runs at the rate of 47 miles per hour toward grand city. they pass each other 4 hours later. find the rate of the train from grand city.

Which geometric principle is used to justify the construction below?