Two large balls roll over a smooth surface and collide. They are made of a super hard material so there is no deformation. Ball $1$ has a mass $m_1$ of $4\mathrm{.}50$ kg and travels with an initial velocity of $2\mathrm{.}67\frac{m}{s}.$ Ball $2$ has a mass $m_2$ of $2\mathrm{.}50$ kg and travels with an initial velocity of $1\mathrm{.}99\frac{m}{s}.$ A diagram of their collision is shown below. After the collision, what is the velocity of $($a$)$ ball $1$ and $($b$)$ ball $2?,$ and: Note: This is a silly problem with silly answers!

Ender and Shen are flying at each other during a battle in

space. Ender moves with a velocity $v_1$ of $9\mathrm{.}821\frac{m}{s}$ while Shen,

with a mass of $51\mathrm{.}0$ kg $,$ moves at a velocity $v_2$ of $7\mathrm{.}65\frac{m}{s}.$

When the two collide, they hold on to each other and move

with a velocity $v_3$ of $5\mathrm{.}348\frac{m}{s}.$ What is Ender's mass, in kg $?$

$($If you would be so kind as to answer all three problems and show all your work, my heart goes out to you. Just know I apreciate it$!)$