Question 1204016
Let the rate of the boat in still water  be {{{s}}} and rate of the current be {{{s[1]}}}.


Distance 

{{{d= 128 mil}}}

Upstream rate = {{{s - s[1]}}}

Downstream rate  = {{{s + s[1]}}}


Time taken to travel upstream 

{{{128/(s-s[1]) = 4}}}

{{{128/4= s-s[1] }}}

{{{s - s[1] = 32}}} ..........eq.1


Time taken to travel downstream 


{{{128/(s+s[1]) = 2}}}

{{{128/2= s+s[1] }}}

 {{{s + s[1] = 64}}} ..........eq.2


add eq.1 and  eq.2


{{{s - s[1] + s + s[1] = 32 + 64    }}}

{{{2s = 96}}}

 {{{s = 48mph}}}


Substituting in eq.2

{{{48 + s[1] = 64}}}

  {{{s[1] = 16mph  }}}


answer:


Rate of the boat in still water  is {{{48(mil/h)}}}

Rate of the current is {{{16(mil/h )}}}