Question 1131020
.


Let me show to you &nbsp;<U>much &nbsp;MORE &nbsp;REASONABLE &nbsp;way</U> &nbsp;to solve it by the Substitution method.


<pre>
7x + 8y = -18      (1)
7x + 5y =  -6      (2)


The term " 7x " is in the first and in the second equation.

Therefore, it is TOTALLY ENOUGH to express 7x from the first equation as  7x = -18 - 8y  and then substitute it into 
the second equation, replacing " 7x " there. You will get then


    (-18-8y) + 5y = -6

    -18 - 8y + 5y = -6

    -3y = -6 + 18 = 12

    y  = {{{12/(-3)}}} = -4.


Now substitute this value  y= -4 into equation (2) to get

    7x + 5*(-4) = -6

    7x - 20 = -6

    7x = -6 + 20 = 14

    x = 14/7 = 2.


<U>Answer</U>.  The solution is  x= 2,  y= -4.


Check the solution on your own by substituting the found values in the given equations.
</pre>

Solved.


---------------


By doing in this way, you avoid working with fractions and denominators.


Less computing - less chance to make an error.