Yvaries inversely as x. yequals=8 when x equals=7. find y when x equals= 2.

First, you need to establish an equation here.

From the statement "y varies inversely as x", we can write
          

Note that this is not an equation. To make it an equation, we must put a constant, k here. Therefore, we can say that
              (equation 1)

When y = 8 , x = 7
Substitute it to equation 1 to find the value of k.

         8 = k * 
           k = 42

Find y when x = 2. Substitute the value of x and k in equation 1 to find y.
 
           y = (42) * 
              y = 21

    
      

Zero is the mid point of the line segment

I'm not sure but i think it's 1670km/h