Answer:
1) solution is y = -7
2.) DNE
3.) Solution is y = -2
Step-by-step explanation:
1.) 2+3 = y + 12
Add the LHS and make y the subject of formula 
5 = y + 12
Y = 5 - 12
Y = - 7
The solution of the equation is - 7
2.) 2 + 13 = 1 +8
Since there is no unknown variable and the sum of the numbers in the left hand side ( LHS ) is not equal to the sum of the numbers in the right hand side ( RHS ), it will be concluded that there is no solution in the equation. 
3.) y - 7 = 2 - 11
Sum the RHS and make y the subject of formula 
Y - 7 = -9
Y = -9 + 7
Y = -2
The solution of the equation is -2
 
        
             
        
        
        
Answer:
0.4 
Step-by-step explanation:
Total seats:
12 + 8 = 20
P(aisle seat) = 8/20 = 0.4
 
        
             
        
        
        
Expression: 
2 * x = 15
Hope that helped!
        
                    
             
        
        
        
X = 2
y = -9
16 - negative 18 = -2