Subtract: (4n + 7) - (7n - 8)

Li buys supplies so he can make and sell key chains. he begins to make a profit only after he sells 4 key chains. what point on the graph makes the most sense in this situation?

Two airplanes start at the same place and travel in opposite directions,one at 395 miles per hour and the other at 422 miles per hour. how many hours will it take for the planes to be 2451 miles apart?

Triangle abc has side lengths: ab = 3.5  cm, bc = 2.4 cm, and ac = 4.2 cmδabc ≅ δhjkwhat is the length of side hj?