You could get two different functions out of this:
<u>2x + 2y = 8</u>
1). <u> 'y' as a function of 'x'</u>
Subtract  2x  from each side:  2y  = -2x + 8
Divide each side by  2 :         <em> y  =  -x + 4</em>
2). <u> 'x' as a function of 'y' :</u>
Subtract  2y  from each side:    2x  =  -2y + 8
Divide each side by  2 :        <em>  x  =  -y + 4</em>
Those two functions look the same, but that's just because the original 
equation given in the problem was so symmetrical.  In general, they're 
not the same function.
        
                    
             
        
        
        
<span>3x − y = 2
y = 3x - 2
x + y = 6
x + 3x - 2 = 6
4x - 2 = 6
4x = 6 + 2
4x = 8
x = </span>

x = 2
Hence, the x co-ordinate is 2.
 
        
        
        
Step-by-step explanation:
30 minutes x an hour and half past prolly around 1 hr and 30 sec
 
        
             
        
        
        
Answer:
7.5m
Step-by-step explanation:
1cm:2.5m
3cm:7.5m
 
        
             
        
        
        
STEP 1:
convert meters to centimeters
100 cm= 1 meter
= 100 cm/m * 2.5 m
= 250 cm
STEP 2:
x= length of first shelf
2x+18= length of second shelf 
x-12= length of third shelf
x+4= length of fourth shelf
since the whole board has to be used, add lengths of all shelves and set it equal to the whole length of the board (250 cm). 
x + (2x+18) + (x-12) + (x+4)= 250 cm
combine like terms
5x + 10= 250 
subtract both sides by 10
5x= 240
divide both sides by 5
x= 48
STEP 3:
find length of second shelf
= 2x + 18
= 2(48) + 18
= 114 cm
CHECK:
x + (2x+18) + (x-12) + (x+4)= 250 
48 + (2(48)+18) + (48-12) + (48+4)= 250
48 + (96+18) + 36 + 52= 250
48 + 114 + 36 + 52= 250
250= 250
ANSWER: Shelf two is 114 cm. 
Hope this helps! :)