How do you find the ordered pair that is the solution of equations 5x - 4y + 3 = 15 and 9y = 4x + 31?

1 Answer
Alan P.
Jul 27, 2016

#(x,y)=color(green)(""(8,7))#

Explanation:

Rearrange the given equations into standard form:
[1]#color(white)("XXX")5x-4y=12#
[2]#color(white)("XXX")4x-9y=-31#

[1]#xx4# minus [2]#xx5#
#color(white)("XXXX")(20x-16y=color(white)("XXx")48)#
#color(white)("XXX")underline(-(20x-45y=-155))#
#color(white)("XXXXXXXXX")29y=color(white)("XX")203#

#color(white)("XXX")rarr y=203/29=7#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Similarly, [1]#xx9# minus [2]#xx4#

#color(white)("XXX")rarr x=8#

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