Question 1054652
Find John's rate.
{{{R[J]*6=5}}}
{{{R[J]=5/6}}}
Find Mary's rate.
{{{R[M]*7=5}}}
{{{R[M]=5/7}}}
So together,
{{{(R[J]+R[M])t=5}}}
{{{t=5/(5/6+5/7)=(5(6)(7))/(5*7+5*6)=210/67}}}
or approximately 3.13 days