If the different between the number of people in the age groups (46 - 55) and (16 - 25) is 0.975 million, then the total population (in millions) of the city is:

Answer: Option B

Difference = 0.975 millions
(18.25 - 15)% = 0.975 millions
3.25% = 0.975
$$\begin{array}{rl}& 1\%=\frac{0.975}{3.25}\\ & 100\%=\frac{0.975}{3.25}\times 100\\ & =30\text{ millions}\end{array}$$