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You are given
f(2) = 7.
It is the exact meaning of this fragment from the post "the point P = (2,7) is on the graph of a function f".
Take x-3 = 2, i.e. x = 2+3 = 5.
Then
g(5) = f(x-3) - 2 = f(5-3) - 2 = f(2) - 2 = (at this point recall that f(2) = 7, so you can continue the equality) = 7 - 2 = 5.
Thus the corresponding point on the graph of the function g is Q = (5,5).
ANSWER. The corresponding point on the graph of the function g is Q = (5,5).
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The lesson to learn from my post is THIS :
The "corresponding point" in this context is the point, whose coordinates you can calculate,
starting from the given point P and using the given definition of the function g.