1. 3/5
2. 15 
3. 1/15
4. 1 2/3
        
                    
             
        
        
        
I believe that -15 is the answer
        
             
        
        
        
Answer:
9 miles per hour
Step-by-step explanation:
 
 
        
             
        
        
        
So, how much acid is there in 6 gallons?  well is 20% acid or (20/100), so the amount of acid in it just (20/100) * 6 or 1.2, the rest is say water.
now, if we want a 90% solution, and say we add "y" gallons, how much acid is in it?  well (90/100) * y, or 0.9y.
now let's add "x" gallons of pure acid, now, pure acid is just pure acid, so is 100% acid, how much acid is there in it?  (100/100) * x, or 1x or just x.
we know whatever "x" and "y" amounts are, they -> x + 6 = y
and we also know that x + 1.2 = 0.9y
 
 
        
        
        
<4 and <2  corresponding angles
<6 and <3  alternate interior angles
<4 and <5 alternate exterior angles
<6 and <7 interior angles on the same side of transversal