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Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?

Interpret the following expression (5y^2-7)^3/(2y)^2