To answer this item, we have 4 as the speed of the kayaker in still water and the speed of current be y.
When the karayaker moves upstream or against the current, his speed would be 4 - y. Further, if he moves downstream or with the current, the total speed would be 4 + y. The time utilized for the travel is equal to the ratio of the distance and the speed. 
 Total time = 9/(4 - y)  + 9/(4 + y) = 6
We multiply the equation by (4-y)(4+y)
              9(4-y) + 9(4 + y) = 6(4-y)(4+y)
Simplifying,
                72 = 96 - 6y²
Transposing all the constants to only one side of the equation and rearranging,
               6y² = 96 - 72
                 y² = 4
                    y = 2
Hence, the speed of the river's current is 2 miles/hr. <em>The answer is letter B.) 2 miles/hour.</em>
        
             
        
        
        
2 times 3 times 4 times 4 times 5 equals 480
        
             
        
        
        
Answer:
3 - 48
 - 48
Step-by-step explanation:
Given
(a + 2)(3a² + 12)(a - 2)
= (a + 2)(a - 2)(3a² + 12) ← expand the first pair of parenthesis using FOIL
=(a² - 4)(3a² + 12) ← expand using FOIL
= 3 + 12a² - 12a² - 48 ← collect like terms
 + 12a² - 12a² - 48 ← collect like terms
= 3 - 48
 - 48
 
        
             
        
        
        
Answer:
Proportional Relationship: I  Not a Proportional Relationship:
y=1.6x                                  I   y=3/(4x)
y=x                                      I   y=2x+1
y=12x .                                 I   y=3+x
Explanation:
I took the test and that's how i got these answers.