Answer:
3x - (15 x 3) = 90 
or 
3x - 45 = 90
Explanation:
there are 3 boxes. We don't know how many are in them yet, so we write this as 3x. However, we know that we give away 15 to 3 different teachers. 15 x 3 = 45 
Therefore the first part is 3x - 45
We also know that in the end we have 90 left.
So our final equation is:
3x - 45 = 90
 
        
             
        
        
        
Answer:
8 9/10 is the largest number 
 
        
                    
             
        
        
        
Answer:
80 m²
Step-by-step explanation:
The area (A) of a trapezoid is calculated as
A =  h (a + b)
 h (a + b)
where h is the perpendicular height between bases and a, b are the bases
Here h = 8, a = 14 and b = 6, thus
A =  × 8 × (14 + 6) = 4 × 20 = 80 m²
 × 8 × (14 + 6) = 4 × 20 = 80 m²
 
        
             
        
        
        
Answer:
Chris will take 0.75 seconds to return to his starting height of 10 feet.
Step-by-step explanation:
Let the height of Chris be represented by  , where
, where  is the height in feet and
 is the height in feet and  , the time in seconds. First, we equalize the formula to a height of 10 feet and simplify the resulting expression, that is:
, the time in seconds. First, we equalize the formula to a height of 10 feet and simplify the resulting expression, that is:


Then, we simplify the expression by algebraic means:

Roots of the polynomial are, respectively:

First root represents the initial height of Chris, whereas the second one represents the instant when Christ returns to the same height above the surface of the water. Hence, Chris will take 0.75 seconds to return to his starting height of 10 feet.