Question 1135156
This might be easier to do as 'seconds'.


I am assuming here, that the third lap is {{{1/10}}}MINUTES LESS than the second lap.  One-tenth of a minute is  6 seconds.

<pre>
LAP NUMBER           MINUTES                   SECONDS
  1                  {{{5/6}}}                        50
  2                  {{{5/6+1/12}}}                   55
  3                 {{{ 5/6+1/12-1/10}}}                49
TOTAL                                           154
</pre>

---problem solution unfinished---
---maybe you can continue---