Question

X-Y=17
X+Y=13
qual o resultado??​

Answer 1

x-y= 17

x= 17+y

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x+y= 13

(17+y) + y= 13

17+y+y=13

17+2y= 13

2y=13-17

2y=-4

y=-4/2 = -2

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x= 17 -2

x= 15