10. which pair of equations below represent perpendicular lines?
a) y = 7/8x + 12and y = -8/7 x – 8
b) y = 5x + 15 and y = -5x + 15
c) y = 4x + 9 and y = 4x -9
d) y = 9 and y = 18

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )

Classify the following number. −9.070707…