Question

x+y=7 3y-3x=-9 me ajudemm

Answer 1

$\left \{ {{x+y=7} \atop {3y-3x=-9}} \right.$

$x = 7-y$

$3y -3(7-y) = -9$

$3y -21+3y = -9$

$6y = 21-9$

$2y = 7-3$

$2y = 4$

$y = \frac{4}{2}$

$\boxed{y = 2}$

$x = 7-y$

$x = 7-2$

$\boxed {x = 5}$

Answer 2

x +y = 7     (.-3)
3y -3x = -9

-3y +3y -3x -3x = -9 -21
-6x = -30
x = 5

y = 7 -5
y = 2