Problem Solving (PS) | A function f(x) is defined as f(x+y)=f(x)+f(y) for all real value of x

A function f(x) is defined as \(f(x+y)=f(x)+f(y)\) for all real value of x and y, and \(f(1)=3\). What is the value of\( f(\frac{2}{3})\)?

A. 0
B. \(\frac{2}{3}\)
C. 1
D. \(\frac{4}{3}\)
E. 2

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