Idon't get how to do it i have tried but i can't i think that it might be 20 i think

Country carpets charges $22 per square yard for carpeting, and an additional installation fee of $100. city carpets charges $25 per square yard for the same carpeting, and an additional installation fee of $70

Which expression can be used to determine the slope of the line that passes through the points -6, three and one, -9

If a || b and b | y, then ? a) x || y. b) x | a. c) a | y. d) a || y.