Question 143544
Distance equals Rate times Time:  {{{d=rt}}}, so Rate equals Distance divided by Time {{{r=d/t}}} and Time equals Distance divided by Rate {{{t=d/r}}}.


First calculate the rate for the first part of the trip:  {{{r=26/4}}}.


Second, take the result of the previous calculation, divide it by 2, and replace r in {{{t=10/r}}} with that result.  Then do the arithmetic.