15 + -26 what is the answer ? i don't get it

If the measure of xyz is 81 what is the measure of yz

If 10 men take 18 days to mow 60 acres of grass, how long will 15 men take to mow 80 acres?

Which statements are true? check all that apply. the line x = 0 is perpendicular to the line y = –3. all lines that are parallel to the y-axis are vertical lines. all lines that are perpendicular to the x-axis have a slope of 0. the equation of the line parallel to the x-axis that passes through the point (2, –6) is x = 2. the equation of the line perpendicular to the y-axis that passes through the point (–5, 1) is y = 1.