This is one of two approaches:
Given:
2x-5y=-4" "..........Equation(1)
color(white)("d") x+6y=+4" "..........Equation(2)
Multiply both sides of Eqn(2) by 2
2x-color(white)("d")5y=-4" ".........Equation(1)
ul(2x+12y=+8" ".........Equation(2_a)larr" Subtract" )
color(white)("d")0-17y=-12
By choosing negative it will change the y term into positive.
Divide both sides by (-17)
color(blue)(color(white)("ddddddddddd")ul(bar(| color(white)(..) y=12/17color(white)(..)|)))
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Substitute for color(red)(y=12/17) into Eqn(2)
color(green)(x+6color(red)(y)=4 color(white)("dddd")->color(white)("dddd")x+(6color(red)(xx12/17))=4 )
color(white)("ddddddddddddd")->color(white)("dddd")x+color(white)("ddd")72/17color(white)("d.d")=4
color(blue)(color(white)("ddddddddddd")ul(bar(| color(white)(..) x=-4/17color(white)(..)|)))
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color(blue)("Check")
2x-5y=-4" "..........Equation(1)
color(white)("d")x+6y=+4" "..........Equation(2)
2(-4/17)-5(12/17)=-4" "..........Equation(1)
color(white)("d")(-4/17)+6(12/17)=+4" "..........Equation(2)
-8/17-60/17=-4" "..........Equation(1)
-4/17+72/17=+4" "..........Equation(2)
-4=-4" "..........Equation(1)
+4=+4" "..........Equation(2)