X+ 5 < 20

solve the inequality above.

Work Shown:

-x+5 < 20

-x+5-5 < 20-5 ... subtract 5 from both sides

-x < 15

-x/(-1) > 15/(-1) ... divide both sides by -1

x > -15

Note how the inequality sign flips when we divide both sides by a negative number.

Alternative method

-x+5 < 20

-x+5+x < 20+x ... add x to both sides

5 < 20+x

5-20 < 20+x-20 ... subtract 20 from both sides

-15 < x

x > -15

We get the same answer.

step-by-step explanation:

points a and b are equidistant from the desired line, so the line you find by using them will go through point r.

using points other than a and b will give the desired line only if they are equidistant from r. if they are randomly located, the perpendicular line you create will not necessarily go through point r, hence will not be a solution to the problem.