Add the mileage together to find total miles.
 Add the hours together.
 Divide total miles by total hours.
305 + 190 = 495 miles
5 + 4 = 9 hours.
495 / 9 = 55 miles per hour.
 
The average speed was 55 miles per hour.
 
        
             
        
        
        
Word form - six.seven
Expand form - 6 + 0.7
        
             
        
        
        
Convert any mixed numbers to fractions. 
Then your initial equation becomes:
15
4
×
4
1
Applying the fractions formula for multiplication,
=
15
×
4
4
×
1
=
60
4
Simplifying 60/4, the answer is
15
        
                    
             
        
        
        
Arc length has a formula that is similar to arc measure, but arc length is expressed in inches or meters or miles, etc., whereas measure is expressed in degrees, like an angle.  The formula for each take this into account.  Since the arc length is part of the length of the outside of the circle, the formula includes the circumference for a circle.  

, where theta is the degree measure of the central angle intersecting the arc you're looking for, and d is the diameter of the circle.  Our formula would look like this with the info we have: 

 which can be simplified to 

 which can be simplified even further to 

.  And that's your answer! 
 
        
        
        
One form of the relation of inverse variation is y = k/x.
first step:  Find the value of k:    Taking the values x=5 and y = 4, 4=k/5, or k=20.  Then,   y = 20/x.
Next:  Let y = 7 and find the corresp. value of x:  7=20/x, or 7x=20, or
x = 20/7    (answer)