What does Δy and Δx stand for

(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.

3x = 729 solve for x plz . it's urgent. will mark

Yvaries inversely as x. y =12 when x=5. find y when x=4