Question

qual o resultado {x+y=10 e x-y=4 ??

Answer 1

x+y=10 ⇒ x=10-y
x-y=4

x-y=4⇒ 10-y-y=4 ⇒ -2y=4-10 ⇒ -2y=-6 ⇒ y=3

x-y=4 ⇒ x-3=4 ⇒ x=4+3 ⇒ x=7

Answer 2

x + y = 10
x - y = 4
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2 x = 14
x = 14/2
x = 7
x + y = 10
7 + y = 10
y = 10 - 7
y = 3