The pattern followed is that in the first row, the number in the middle is obtained by adding the other two and dividing the result by 3.
Eg : $$\frac{24+36}{3}=\frac{60}{3}=20$$
and $$\frac{15+18}{3}=\frac{33}{3}=11$$
Similarly, $$\frac{55+x}{3}=40$$
=> $$x=120-55=65$$
=> Ans - (D)
Create a FREE account and get: