Aline that contains the point (-8,-1) and is perpendicular to -15x +3y = 9

Put the other line in point slope form...(solve for y :D )

3y=15x+9

y=5x+3, so this line has a slope of 5

For a line to be perpendicular to another the slopes have to be negative reciprocals of each other...mathematically...

s1*s2=-1

So for the other line to be perpendicular to the first:

5m=-1, m=-1/5, thus our other line (so far) is:

y=b-x/5, now we can use the point (-8,-1) to solve for the y-intercept, "b":

-1=b-(-8)/5

-1=b+8/5

-1=b+1.6

b=-2.6

So the perpendicular line that contains the point (-8,-1) is:

y=-0.2x-2.6

The answer is 41.7 because 1.39 times 30 is 41.7