if a speedomter reads in lm per hour and the legal speed limit is 55mi/h and you want to know how fast she can drive ? would I multiply the 55 x 6 to get km

Do you mean that it reads in km per hour? I never heard of an lm per hour.

Why would you multiply by 6?

yes I meant km I fiqured that you would reverse it

In km/hr, the speed limit is
55 miles/hr * 1.609 km/mile = 88.5 km/hr