What is the length of the hypotenuse in this right triangle ?

There is a line with slope 1/a going through the point (a, a²). find the equation of the line perpendicular to this line at this point. (don’t let this problem intimidate you! solve the problem as you would if i’d given you specific values. just use variables instead.)

45% of the trees in a park are apple trees. there are 27 apple trees in the park. how many trees are in the park in all?

How can you find the mean absolute deviation (mad) for this set of data?