Which unit should be studied to review symbols from set theory?

How do i do this activity, is appreciated

*let m∠cob = 50°30’, m∠aob = 70° and m∠aoc = 20°30’. could point c be in the interior of ∠aob? why? a. point c could be the interior of aob but it is not the only case b. point c is the interior of aob c. point c is not the interior of aob d. the given is not possible for the plane geometry answer

Complete the steps to find 4.830 ÷ 5