Answer:  19.8 ft 
Step-by-step explanation:
Use the Pythagorean Theorem formula to solve for how high the top of the ladder reach.  
The formula says  a^2 + b^2 = c^2 
Where a and b are the two legs and  C is the hypotenuse. 
In this situation, the hypotenuse will be length of the ladder , and either  a or b will be the length of the ladder from the building or the length of how long the ladder. 
a will be 3 ,  and c will be 20. Input in the values  into the formula and solve for b. 
3^2 + b^2 = 20^2 
9 + b^2 = 400 
-9              -9 
  b^2 = 391   
     b =  
 
   b  = 19.77371   round to the nearest tenth is ,  19.8 
 
        
             
        
        
        
Answer:
 -6 because I did it on my calculator
 
        
             
        
        
        
It would be 2020-1836 = 184 years ago
        
             
        
        
        
D.  He will have $2,121.80.
After one year at 3% interst, $2000 becomes $2000 x 1.03 = $2,060.
During the second year, that $2060 x 1.03 becomes $2121.80
        
                    
             
        
        
        
Answer:
3.75 quarts, rounded to 3.8 quarts
Step-by-step explanation:
3 quarts of solution is 10% antifreeze, so 0.3 quarts are already antifreeze, and 2.7 quarts are not. 
a(the antifreeze we already have)+x(what we're going to add)= 1.5*2.7
Let me explain. If we have 60% antifreeze, 40% is not. 60/40=1.5
Substitute a for 0.3
0.3+x=4.05  Subtract 0.3 from both sides
x=3.75