The drawing shows a collision between two pucks on an air$-$hockey table. Puck A has a mass of $0\mathrm{.}21kg$ and is moving along the $x$ axis with a velocity of $5\mathrm{.}20\frac{m}{s}.$ It makes a collision with puck $B,$ which has a mass of $0\mathrm{.}42kg$ and is initially at rest. After the collision, the two pucks fly apart with angles as shown in the drawing and $($:$=40$