Questions

In each row, 

Sum of 1st two digit number + last two digit number = Middle two digit number

i.e., 1st row 15 + 40 = 55

2nd row 46 + 47 = 93

Similarly, 7x + 16 = 87 => x = 1.

Half the Product of Number in the upper & lower box gives the number in the middle box.

i.e. 18 x 4/2 = 36

15 x 6/2 = 45

In the same way 

8 x N/2 = 44 => N = 11.

The capital of Bangladesh “Dhaka” is the world’s most crowded city with a population density of 44,500 people per square kilometre, released by World Economic Forum (WEF), citing UN Habitat data. According to UN Habitat data, of the top 10 most densely populated cities in the world, six are in Asia, three are in Africa and one is in South America. India’s financial capital Mumbai, home to 31,700 people per square kilometre has acquired second place, where as Kota in Rajasthan with 12,100 people per square kilometre was ranked seventh. Others in the list include Medellin in Columbia (3rd), Manila in Philippines (4th, 14,800), Casablanca in Morocco (5th, 14,200), Lagos in Nigeria (6th, 13,300), Singapore (8th, 10,200) and Jakarta in Indonesia (9th, 9,600).