Trisha needs 41/2 yards of fabric to do a project. if she already has2/3 of a yard of fabric, what is the minimum amount of fabric she must buy to be able to complete her project?

We know that
4 1/2> (4*2+1)/2> 9/2
(2/3)*(9/2)> 18/6>3 yd  (this is what Trisha has )
if she has (2/3) she only needs (1/3)

[the minimum amount of fabric she must buy]=(9/2)*(1/3)=1.5 yd

the answer is 
the minimum amount of fabric she must buy is 1.5 yd