The area is 21cm squared. u would have to find the length of the bottom triangle which is 14. than multiply that by the height which is 3. finally divide that all by 2 and youll get the area
        
             
        
        
        
I don't really speak Spanish but I'll guess that says
 How do I solve  y = 1 - 2.5
Unless I'm missing something, there's not even any algebra here.  
The way we subtract a bigger number from a smaller number is first we subtract the smaller number from the bigger number the regular way, then we prepend a minus sign.
y = 1 - 2.5 = -(2.5 - 1) = -1.5
        
             
        
        
        
Answer:

Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
28
Step-by-step explanation:
area = width x height
area = 7 x 4
area = 28 square feet