According to the given data we have the following:
A person is travelling at 75 mph
In order to calculate the speed in kmh we would have to make the following calculation:
So, if we know that 1 mph is 1.609344 kmh, then the speed of 75 mph at kmh would be:
speed in kmh=75 mph*1.609344 kmh
speed in kmh=120.7008 kph.
Therefore, If I am traveling at 75mph the speed in kmh would be of 120.7008 kph.