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x a z b y
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In this picture I showed the number line by (-------), the points x = and y = and the point z, whose position is under the question.
I also denoted by "a" the distance from x to z and by "b" the distance from z to y.
We are given that = , and the problem asks to find b.
We have these two equations
a + b = - = , (1) and
= . (2)
From (2), a = . Substitute it into (1). You will get
+ b = , which is equivalent to
= .
It implies b = = .
Answer. The distance from z to y is .
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In his solution, @josgarithmetic outputted the value of the coordinate of the point z, although the problem asked for the distance from z to y.
It is the source of the difference between his answer and the answers by the tutor @greenestamps and mine.