Question

solve by substitution

3x-2y=5
4x-5y=2

Answer 1

3x-2y=5
4x-5y=2
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3x-2y=5
x=(5+2y)/3
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4x-5y=2.
4(5+2y)/3-5y=2
(4(5+2y))/(3)-5y=2

(4(2y+5))/(3)-5y=2

(4(2y+5))/(3)-5y*(3)/(3)=2

(4(2y+5))/(3)-(15y)/(3)=2

(4(2y+5)-(15y))/(3)=2

(-7y+20)/(3)=2

-7y+20=6

-7y=-14

y=2
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x=(5+2y)/3
x=(5+2(2))/3
x=3

Answer 2

pick either equation and solve for either x or y
then use the expression created (for example x=blah) to substitute in the other equation)
x+2y=0, will become blah+2y=0
to get the first expression created for x=blah you will eliminate every x, since the only x you can get is the first one in x=...
hence you will be left with an equation containing only y and you can solve for y