(x+3)^3=343, find the value of x^3
$$\begin{array}{rcl}(x+3)^3 & = & 343 \quad | \quad \sqrt[3]{} \\x+3 & = & \sqrt[3]{343} \\x+3 & = & \sqrt[3]{7^3} \\x+3 &=& 7 \quad | \quad -3\\x &=& 4 \\x^3 &=& 4^3 \\x^3 &=& 64\end{array}$$
