An airplane crooses the United States from San Francisco to Boston in 4 hours 20 min. Find the average speed if the distance is 4330 km.

999.23 km/h

Explanation:

We can use the formula for average speed as "Distance divided time" to solve the problem.

Let's start by writing the time in hours: 4 h and 20 min is the same as 4 hours + 1/3 of an hour = 13/3 of an hour

Now we use this number in the quotient for average speed:

Average speed = 4330 km / (13/3) h = 12990 / 30  km/h = 999.23 km/h

the answer is c. the lower legs are levers, and the knees are fulcrums. the ankles hold the loads.