I'm assuming you mean how many mph when you refer to how fast the car was going.
So 300 km = 1.5 hrs
1.) Find the number of km per hour
Since we have the equation 300km = 1.5hr, we can just divide 1.5 (to isolate the number of hours) on both sides.
You should get 200 km = 1 hour
2.) Convert km to miles
To do this, you must know the conversion 1 km = 0.621371192 miles
So to convert 200 km to miles, just multiply 200 x 0.621371192.
You should get 124.274238.
That means the Ferrari drove at a pace of roughly 124 mph :)