Find area and perimeter of shaded area and the perimeter is not 96

The polygon tool to draw a rectangle with a length of 5 units and a height of 3 units. one of the sides of the rectangle falls on line ab , and the rectangle has a vertex of a. each segment on the grid represents 1 unit.

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.)

Due to bad planning, two of the local schools have their annual plays on the same weekend. while 457 people attend one, and 372 attend the other, only 104 people were able to attend both. how many people went to at least one play?