• Did you manage to make any progress? For example, could you find $\bf v$ and $\bf w$? – Minus One-Twelfth Mar 14 at 9:25
• Here's a hint: imagine from usual algebra if you knew $a+b$ and $a-b$, could you work out the values of $a$ and $b$ (for example if $a+b=100$ and $a-b=10$, can you find what $a$ and $b$ are)? Pretty much same method would work here for finding $\bf v$ and $\bf w$. – Minus One-Twelfth Mar 14 at 9:29
• Correct! $\color{grey}\,$ – Minus One-Twelfth Mar 14 at 9:58
• To divide a vector by a number, simply divide each component by that number. Once you know what $\bf v$ and $\bf w$ are, you should know how to find the angle between them using dot products (if not, it would be best to revise how to do so). – Minus One-Twelfth Mar 14 at 10:21