The cost of a car is 400% greater than the cost of a bike. If there is an increase in the cost of the car is 15% and that of bike 20%. Then the total increase in the cost of the 5 cars and 10 bikes is:

Let the bike's initial cost be x and then car's initial cost be 5x
After the increase,
Bike price = 1.2x
Car price = 5.75x
Initial total cost of 5 cars and 10 bikes,
= 25x + 10x = 35x
New cost,
= 28.75x + 12x = 40.75x
Change in cost = (40.75x - 35x) = 5.75x
% change = $$\frac{{5.75{\text{x}} \times 100}}{{35}} = 16\frac{3}{7}\% $$