The correct answer to this question is this one: "4/45"
inverse variation ---> wt = constant
let wt=k
put w=4, t= 1/5 and find k
So the correct answer for k is 4/5
wt = 4* (1/5) = 4/5 = k\
so your function is
wt = 4/5 or t= 4/(5w)
now to get t, when w=9, just put w=9 in t=4/(5w)
So that makes 4/45
