20% of what number is 18?

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.)

Use the graph of the sine function y=2sinθ shown below

What are the solutions of the system? solve by graphing. y = -x^2 - 3x + 2 y = -2x + 2