pa sagot please
9-13. Find the value of the constant of variation k. Write your answer before the number.
9. p varies directly as q and inversely as r. If p = 36 when q = 2 and r = 3
10. a varies directly as b and inversely as c. If a = 9 when b = 6 and c = 2.
11. z varies directly as x and inversely as y. If z = 6 when x = 8 and y = 9.
12. If r varies directly as s and inversely as the square of t. If r = 2 when s = 18 and t = 2.
13. x varies directly as the square of y and inversely as z. If x= 12 when y = 3 and z = 6.​