Question 428471
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I need to use substitution method
15x - 10y = 1
5y = -2 + 15x
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        It can be solved in much more efficient way than @mananth does it in his post.


        I will apply a  " smart "  substitution method.



<pre>
Your starting equations are 

    15x - 10y = 1    (1)
    5y = -2 + 15x    (2)


From equation (2), express  15x = 5y + 2 and substitute it as a whole block into equation (1), 
replacing the term 15x there


    (5y + 2) - 10y = 1,

     5y - 10y = 1 - 2,

        -5y   =   -1

          y   =   1/5 = 0.2.


Now substitute y = 0.2 into equation (1) and find x


    15x - 10*0.2 = 1,

    15x - 2 = 1,

    15x = 1 + 2 = 3,

      x = 3/15 = 0.2.


<U>ANSWER</U>.  x = 0.2,  y = 0.2.
</pre>

Solved.


As you see, &nbsp;in this case &nbsp;" smart " &nbsp;substitution works more effectively 
than a standard &nbsp;"  stupid " &nbsp;substitution.



The meaning of this problem for you is to learn advantages of "smart" substitution method.