$<br>$A proton $($mass $1,6\times 10 -27\mathrm{????}\mathrm{????})$ collides with a neutron $($with essentially the same mass as the proton$)$ to form a particle called a deuteron. What is the velocity of the deuteron, if it is formed from a proton moving with velocity $8\mathrm{.}2\times 10\mathrm{⁶}\frac{\mathrm{????}}{\mathrm{ ????}}$ to the right and a neutron moving with velocity $5\mathrm{.}1\times 10\mathrm{⁶ }\frac{\mathrm{????}}{\mathrm{????}}$ to the left?