In the following pie-chart, the distribution of the number of cars in four major cities is given. In…

Out of the total 1,47,000 cars, City D has 28% of the cars, or $0.28 \times 1,47,000$ $= 41,160$ cars. With a diesel-to-petrol ratio of $3 : 11$, the number of diesel cars in City D is $\frac{3}{14} \times 41,160$ $= 8,820$. City B has 26% of the cars, or $0.26 \times 1,47,000$ $= 38,220$ cars, and with a diesel-to-petrol ratio of $6 : 7$, the number of petrol cars in City B is $\frac{7}{13} \times 38,220$ $= 20,580$. The required difference is $20,580 - 8,820 = 11,760$.