Question

3(x+y)+2(x-y)=17
5(x+y)+4(x-y)=29
señala el valor de 3x+4y-xy

Answer 1

3x+3y+2x-2y=17
3x+2x+3y-2y=17
5x+y=17

5x+5y+4x-4y=29
5x+4x+5y-4y=29
9x+y=29

-1(5x+y=17)
9x+y=29
———————
-5x-y=-17
9x+y=29
———————
4x+0y=12

4x=12
X=12/4
X=3

5x+y=17
Y=17-5x
Y=17-5•3
Y=17-15
Y=2

X=3
Y=2