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solving for x

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3 Answers

Hi Monet;
9c-4x=7
Let's begin with subtracting 9c from both sides...
-9c+9c-4x=7-9c
-4x=7-9c
Let's divide both sides by -4...
(-4x)(-4)=(7-9c)/-4
x=(7-9c)/-4
Let's multiply the right side by -1/-1
x=[(7-9c)/-4](-1/-1)
x=(9c-7)/4
 

Comments

Heh, and all the tutors go "An unanswered linear equation! RAWR!"
 

Comment

9c - 4x = 7
 
9c - 4x -9c = 7 - 9c (subtract 9c from both sides to get the x term by itself on the left)
 
-4x = 7 - 9c (simplify, -9c eliminated from left side of equation)
 
-4x      7 - 9c
----- = -------- (divide both sides by -4 to get x by itself)
 -4          -4
 
       7 - 9c
x = --------- (simplify, equation is now solved for x)
          -4
 
       9c - 7
x = -------- (alternate form, multiplied top and bottom by -1 to eliminate negative sign on denominator)
          4
 
There you go!
 
9c - 4x = 7
 
9c -4x +4x = 7 + 4x => 9c = 7 + 4x
 
9c -7 = 7 + 4x -7 => 9c - 7 = 4x
 
(1/4)(9c - 7) = (1/4)*4x => x = (9c-7)/4