Answer:
 or
 or 
Step-by-step explanation:
We use casework on when  and when
 and when  .
.
For the first case,  , we add 9 to both sides to get
, we add 9 to both sides to get
 .
.
Dividing both sides by 3 gives 

For the second case,  , we add 9 to both sides to get
, we add 9 to both sides to get
 .
.
Dividing both sides by 3 gives
 .
.
Checking both cases, we plug in  and
 and  .
. 
For the first case, we have  ,  which satisfies the equation.
,  which satisfies the equation.
For the second case, we have  , which also satisfies the equation.
, which also satisfies the equation. 
This gives us two solutions to the equation;  and
 and  .
. 
 
        
             
        
        
        
The previous population was 14000.
Explanation
The population decreased by 35% since the last measurement. So the current population is less than the previous population. 
current population=9100
previous population =x
current population is 35% less than the previous population x

The previous population was 14000.
 
        
             
        
        
        
Answer:
xy+2x+3y+6=xy-5 .............(1)
xy-3x+2y-6=xy.....,.,(2)
2x+3y=-11
-4x+2y=6
first equation multiply by 2 
(2)*(2x+3y)=-11 
4x+6y=-22
-4x+2y=6 
8y=-16 y=(-2),,,,, x=(-2,5)
 
        
             
        
        
        
Answer:
The amount of steel used = 94.38 
Step-by-step explanation:
Height of the tank = 4.5 m.
Diameter of the tank = 4.2 m.
But,
radius = 
            = 
radius  = 2.1 m
Total surface area of a cylinder = 2 rh + 2
rh + 2

                                       = 2 r(r + h)
r(r + h)
                                       = 2 x  x 2.1 (2.1 + 4.5)
 x 2.1 (2.1 + 4.5)
                                       = 44 x 0.3 (6.6)
                                       = 87.12
Total surface area of a cylinder = 87.12 
Since  of the steel was wasted, then;
 of the steel was wasted, then;
 x 87.12 = 7.26
 x 87.12 = 7.26 
Actual area of steel sheet used = 87.12 + 7.26
                                                      = 94.38 
Thus, 94.38  of steel was used in making the tank.
 of steel was used in making the tank.