Question

3x - 4y = 15
-2x +3y = -12​

Answer 1

3x -4y = 15

-2x + 3y = -12

9x - 12y = 45

-8x + 12y = -48

x = -3

3(-3) -4y = 15

-9 - 4y = 15

-9-15 = 4y

-24 = 4y

-6 = y

Answer 2

Explicación:

3x - 4y = 15   ==> 3x = 15 +4y  ==> x = 15/3 + 4y/3 => x = 5 + 4y/3

-2x +3y = -12

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-2(5 + 4y/3) + 3y = -12

-10 - 8y/3 + 3y = -12

-10 + y/3 = -12

y/3 = -12 + 10

y = -2 * 3

y = -6

Reemplazamos:

x = 5 + 4(-6) / 3

x = 5 + (-24/3)

x = 5 + ( -8 )

x = 5 - 8

x = -3