The equations x+y=3x+y=3x, plus, y, equals, 3 and -5x-5y=-15−5x−5y=−15minus, 5, x, minus, 5, y, equals, minus, 15 are graphed in the xyxyx, y-plane. Which of the following must be true of the graphs of the two equations?

Afish fossil is found in a rock. a foot bone and tooth are found in an older layer of the same rock. what can scientists learn from the rock? a) the area changed from land to water. b) the area changed from water to land. c) the area has always been land. d) the area was once an ocean.