<PRE><B>Question 744680</B>
5x + 3y = 4 ....(1)
x  - 4y = 3 ....(2)

You now multiply line (1) by 4 and line (2) by 3
This is done to remove one of the unknowns namely &#39;y&#39;

20x + 12y = 16
3x  - 12y = 9

Add

23x      = 25
  x      = 25/23

Substitute x = 25/23 into x - 4y = 3 ...(2)

      25/23 - 4y = 3

           - 4y = 3 - 25/23

Change 3 to 23rds  

           - 4y = 69/23 -25/23

           -4y = 44/23

            -y = 44/92

             y = - 44/92 = -22/46 = -11/23

           x = 25/23 :  y = -11/23
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