Question

x+y=15
x-y=15


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Answer 1

Resposta:

{x + y = 15

{x - y = 15

x + y = 15

x = 15 - y

x - y = 15

(15 - y) - y = 15

15 - y - y = 15

15 - 2y = 15

2y = 15 - 15

2y = 0

y = 0/2

y = 0

x + y = 15

x + 0 = 15

x = 15 - 0

x = 15

x + y = 15

15 + 0 = 15

x - y = 15

15 - 0 = 15