80. 
The opposite side of the arc is equal to its opposite.
 
        
             
        
        
        
We know f(x)=5x+1. Plug in f(x) in the g(x) function.
We get 

 Distribute the 2 to 5x and 1.

Simplify to get 

Now, we plug in -1 for x.


 
 
 
        
        
        
Answer:
y = x² − 6x − 27
Step-by-step explanation:
To distribute, you can use something called FOIL.  It stands for First, Outer, Inner, Last.
First, multiply the First term in each factor.
x · x = x²
Now multiply the Outer terms in each factor.
x · 3 = 3x
Next multiply the Inner terms in each factor.
-9 · x = -9x
Finally, multiply the Last terms in each factor.
-9 · 3 = -27
Add them all up:
x² + 3x − 9x − 27
x² − 6x − 27
 
        
             
        
        
        
If x is the hypotenuse then
hyp^2 = 4^2 + 5^2
hyp^2 = 41
hypotenuse =
<span>
<span>
<span>
6.403124
</span></span></span>
if x is a leg then
leg^2 = 5^2 - 4^2
leg^2 = 25 - 16
leg^2 = 9
leg =3