Answer:
$1,080
Step-by-step explanation:
To solve, we can make a proportion 
14 lessons are $210 and 72 lessons are $x 
14/210=72/x
Cross multiply 
14*x=210*72
14x=15120 
To solve for x, we need to get x by itself. Since x is being multiplied by 14, divide both sides by 14. 
14x/14=15120/14
x=1080 
So, 72 lessons will cost $1,080
 
        
                    
             
        
        
        
Answer:
.01%*
Step-by-step explanation:
Individually, they both have a rate of failure of 1%. 
.01 x .01 = .0001
Therefore they have a combined probability of failure of .01%
*Disclaimer!!
I am not the best at this area in math so I would still reference against someone else's answer, but this is my best effort :)
 
        
             
        
        
        
Answer:
b
Step-by-step explanation:
 
        
             
        
        
        
Hello : 
x²+x - 2 =0
a=1   b=1   c = -2
<span>The sum of the roots is : S = -b/a 
</span>S = - 1/1 = -1