Answer:
4 seconds to reach 200 feet
Step-by-step explanation:
You can use Desmos (graphing calculator) then plug in the equation and you will find the x-values are 7.188 and 0- the origin. 
Divide 7.188 by 2 (this is also solving for the midpoint/axis of symmetry) and you get 3.594
Round 3.594 to the nearest second which would be 4 seconds. 
Hope that helps and have a great day!
 
 
        
             
        
        
        
For this case we have the following equations:
 y = 60x + 40
 y = 50x + 80
 Equaling both equations we have:
 60x + 40 = 50x + 80
 From here, we clear the value of x:
 60x - 50x = 80 - 40
 10x = 40
 x = 40/10
 x = 4 weeks
 Substituting x = 4 in any of the equations we have:
 y = 60 (4) + 40
 y = 240 + 40
 y = 280 $
 Answer:
 $ 280 4 weeks
        
             
        
        
        
        
Answer    
Find out the what fraction of the sandcastle did they build together .
To prove 
Let us assume that the fraction of the sandcastle  they build together be x .
As given


Than the equation becomes

L.C .M of (3,7) = 21
solving


Therefore the fraction of the sandcastle did they build together be 

Hence proved
 
        
             
        
        
        
VW=CD since they are congruent figure, so CD=6