Respuesta :

Answer:

x = 12

Step-by-step explanation:

To find "x", we need to isolate it. This means move "x" to the left side, and everything else to the right side.

When moving a number, do its reverse operation to the entire equation.

x + 9 = 2x - 3

x - 2x + 9 = 2x - 2x - 3         Subtract 2x from both sides

-x + 9 = -3                              

-x + 9 - 9 = -3 - 9           Subtract 9 from both sides

-x = -12

-x/-1 = -12/-1          Divide both sides by -1 to get rid of the negatives

x = 12                     Final answer

Check your answer. Split the equation for the left and right sides. Substitute "x" for the answer "12".

LS:   (left side)

x + 9

= 12 + 9              Add

= 21

RS:   (right side)

2x - 3

= 2(12) - 3            Multiply before subtracting

= 24 - 3               Subtract

= 21

Both sides equal to 21 when "x" is 12.

LS = RS          left side equals right side

Therefore the answer is correct.