A stationary source is emmitting sound at a fixed frequency `f_(0)`, which is reflected by two cars approaching the source. The difference between the frequencies of sound reflected from the cars is `1.2%` of `f_(0)`. What is the difference in the speeds of the cars (in km per hour) to the nearest integer ? The cars are moving at constant speeds much smaller than the speed of sound which is `330 ms^(-1)`.