Answer:
We must add 400 ml of water.
Step-by-step explanation:
We can use the following equation:

Where:
- C(i) is the initial concentration of the solution (80%)
- C(f) is the final concentration of the solution (30%)
- V(i) is the initial volume (150 ml)
- V(f) is the final volume
Now, we just need to solve the equation for V(f).



Therefore, we must add 400 ml of water.
I hope it helps you!
 
        
             
        
        
        
Answer:
vertex = (2, - 9 )
Step-by-step explanation:
Given a quadratic in standard form : ax² + bx + c : a ≠ 0
Then the x- coordinate of the vertex is
 = -
 = - 
x² - 4x - 5 ← is in standard form
with a = 1, b = - 4, thus
 = -
 = -  = 2
 = 2
Substitute this value into the quadratic for corresponding value of y
(2)² - 4(2) - 5 = 4 - 8 - 5 = - 9
vertex = (2, - 9 )
 
        
             
        
        
        
First you have to subtract 35 on both sides, then you would have to divide by 90
        
                    
             
        
        
        
Answer:
102.62
Step-by-step explanation:
I converted everything to inches and then solved for x by putting 58 in. over 66 in. (the girls shadow in in.) and the X in. over 1500 in. I cross multiplied (58 x 1500 and 68 x X) and then divided 68 by the result of 58 x 1500.