Question 206226
1) I'll do the first one, you can do the second one
{{{ m =  ( M[o] / (sqrt(1- (v^2/c^2))) )}}} 
where {{{m[o] = 80}}} and {{{v= 0.8c}}}
Substituting those values yields:
{{{ m =  ( 80 / (sqrt(1- ((0.8c)^2/c^2))) )}}} 
{{{ m =  ( 80 / (sqrt(1- (0.64c^2/c^2))) )}}} 
{{{ m =  ( 80 / (sqrt(1- 0.64) ) )}}}
{{{ m =  ( 80 / (sqrt(0.36) ) )}}}
{{{ m =  ( 80 / (0.6) )}}}
{{{m = 133.33}}} kg

Now you use the same process, except this time the good Captain is moving at 0.9c.
You have the con!