In the year 2015, the number of vehicles of type A and D together is what per cent of the number of vehicles type F and A together in 2016?

In the year 2015, there were a total of 142,980 vehicles, the number of vehicles of type A and D is 20% and 15% of the total. 

Together, it will be 15+20 = 35% of 142,980 = $$\ \frac{\ 35}{100}\times\ 142,980\ =50,043$$

In 2016, F & A together will be 39% of the total ( 18% and 21%)

This will be = $$\ \frac{\ 39}{100}\times\ 186,400\ =72,696$$

Now, the number of vehicles of type A and D together as a percentage of the number of vehicles type F and A together in 2016 will be: 

$$\ \frac{\ 50,043}{72,696}\times\ 100\ =68.83\%$$