Hello,

The picture above shows the question marked by red color and the correct solution. What I don’t understand is that If y < 0 then shouldn’t this equation x + |y| - y = 6 be equal to x - y + y = 6? Shouldn’t x+|x|+y=7 equal to x + |x| - y = 7 ? Thank you.

No, and you can think of this by choosing a negative number. When y < 0, |y| = -y (as y is negative, -y is positive) but this obviously does not apply to y itself as that will be negative when y is negative (as expected). The same applies to the other part of your question.

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