This year
2:7
18:?
well 2*9=18
so 7*9=63
18/63
(18+63=total 81 students)
Last year
1/8
multiply by 9
9/72
9 less students this year
keeping in mind that perpendicular lines have negative reciprocal slopes, let's check for the slope of the equation above

well then therefore

so we're really looking for the equation of a line with slope of -1/3 and that passes through (1, -3 )

Is there a picture i could see?
The answer is B, because the numbers in the equation are 2, and -3x. The signs have to stay with the numbers they are with. So if you move the 3 to the front you have to keep the negative with it.
Amy is constructing an equilateral triangle. it's she joins the centers of the 2 circles to the point of intersection she will be done
option a