Question

Which of the following would not be the result of a substitution in the following system?

2x + y = 7
y - x = 1

7 - 2x - x = 1
2x + x + 1 = 7
2(y + 1) + y = 7

Answer 1

its not 1

Answer 2

why?
2x+y=7
y-x=1
y=1+x
2x+x+1=7

Answer 3

thanks:)

Answer 4

please really excuse when i do mistakes)

Answer 5

@hhelpplzzzz @AlexKross
still incorrect, please read the question carefully:
"following would NOT be the result "

Answer 6

okay thanks