How do I do this? Anyone know

(c) the diagram shows the first three shapes of a matchsticks arrangement. first shape = 3second shape = 5third shape = 7given m represents the number of matchstick used to arrange the n'th shape.(i) write a formula to represent the relation between m and n. express m as the subjectof the formula.(ii) 19 matchsticks are used to make the p'th shape. find the value of p.

I’m confused on how to work the pie charts

Solve for x: 5/3 x = 20/21 it's fraction. remember to simplify your fraction