Can someone please help me

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c

(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.