Question 121513
1.{{{C+I=2.4}}} China (C) plus India (I) equals 2.4 (billion).
2.{{{I=(4/5)C}}} India is 4/5 of China in population.
Substitute 2 into 1.
{{{C+I=2.4}}}
{{{C+(4/5)C=2.4}}}
{{{(9/5)C = 2.4}}}
{{{C=2.4*(5/9)}}}
{{{C=1.33}}}
{{{I=(4/5)C}}}
{{{I=1.07}}}
Rounding to the nearest tenth of a billion, 
{{{C=1.3}}}
{{{I=1.1}}}