The maximum speed of the tupolev tu -144 airliner is 694 m/s. what is this speed in kilometers per hour?

The answer is 2498.4km/h

The speed is 

1 m = 0.001 km          ⇒        694 m = 694 * 0.001 km = 0.694 km
1 h = 60 min = 60 * 60 s = 3600 s 

Therefore:

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.