Points q, r, s, t, are plotted on the number line below

Having a hard time understanding this question (see attachment).

Find the power set of each of these sets, where a and b are distinct elements. a) {a} b) {a, b} c) {1, 2, 3, 4} show steps

Roderick wants to draw a circle for which the numerical value of the circumference is greater than the value of the area.which lengths could he use for the radius? check all that apply