Answer:
24 cats: 28 dogs 
Step-by-step explanation:
28/21 = 1.33
18 x 1.33 = 24
 
        
             
        
        
        
(2,1) is the solution because its where they both intersect..
        
             
        
        
        
Answer:
-11 + 4
Step-by-step explanation:
When you subtract a negative the sign will  switch to plus, so it this case you would switch the - (-4) to a + 4 but you don't change the -11 at the front.