Question 668502
3rd Term: 


(n C k)*(A)^(k)*(B)^(n-k)


(5 C 3)*(2/3x)^(3)*(y)^(5-3)


10*(8/27x^3)y^2


(80/27)x^3y^2


So the third term is <img src="http://latex.codecogs.com/gif.latex?\Large \frac{80}{27}x^3y^2" title="x" />