Ok so first following the order of opperation (P.E.M.D.A.S.)
We have to multiply first so 1/4*4/9 is 4/36
2/3-4/36
We have to get them both to have the same denominator
What times 3 is 36? 12
So multiply 2*12 and 3*12 you get
24/36-4/36=5/9(simplified)