Answer:
Step-by-step explanation:
2x+5y=12
3x+4y=11
---------------
3(2x+5y)=3(12)
-2(3x+4y)=-2(11)
-----------------------
6x+15y=36
-6x-8y=-22
-----------------
7y=14
y=14/7=2
2x+5(2)=12
2x+10=12
2x=12-10=2
x=2/2=1
x=1, y=2. (1, 2)
---------------------
I just provided you an example of a system of equations and I already solved it for you. 
 
        
             
        
        
        
 48 = -18x is an equivalent expression because you just subtact -18 from both sides.
        
                    
             
        
        
        
-2y-11=Z
n/4 -5=m
.................
        
             
        
        
        
The equation is that of a parabola, meaning that the maximum (or sometimes minimum) is 1/2 the sum of the solutions found using the quadratic equation. 
y = 0 for the 2 solutions to {-b +/- sqrt[b2 - 4ac]} / 2a, where a = -3, b = 152 and c = -1150 from the equation for y. Plug a, b and c into the quadratic formula to get x = 9.2571 and x = 41.4095 as the 2 solutions. 
9.2571 + 41.4095 = 50.6666... and the midpoint is 25.3333...
When x = 25.3333..., y = 775.33333.....
To the nearest cent, x=25.33 results in a profit of 775.33.
When x=25.25, Y = 775.31
When x=25.4, Y = 775.32
These are both less than 775.33 when x = 25.33.
 
        
             
        
        
        
Answer:
x = 3
Step-by-step explanation:
5(2 - x) = 7x - 26
Distribute;
10 - 5x = 7x - 26
Add 5x to both sides;
10 = 12x - 26
Add 26 to both sides;
36 = 12x
Divide both sides by 12;
x = 3