( % revenue from data transfer/100 ) = X
ARDT = Y

Question 1 :

X * total revenue = Y * volume
as total revenue is same volume = X / Y
we need to find countries with same volume. if X/Y = const then the plot will be a straight line passing through the origin. so in this case we are looking for pair of countries that will fall in the line that can pass through the origin, only pair that can form the line passing through origin is UK and Spain.

Question 2 :

X * total revenue = Y * volume
total revenue = Y * volume / X
as volume is same, the ratio of total revenues of India and singapore will be
(totat revenue - India)/(total revenue singapore) = (Y/X) - India / (Y/X)-Singapore
(Y/X) - India = 1/9
(Y/X)-Singapore = 9/20
(totat revenue - India)/(total revenue singapore) = (1/9)/(9/20) = 20/81 ~ 1/4
(total revenue singapore) = 4 * (totat revenue - India)

Question 3 :

During 2010,
27 * 2R = ARDT (India) * V
36 * R = 6 * V
ARDT(India) = (27 * 2 * 6) / 36 = 27/3 = 9
Current value of ARDT(India) = 1
so % change = [ ( 9 - 1 ) / 1 ] * 100 = 800%