Question 738955
Two things come to mind while just reading the description one time:
(rate)*(time)=(distance), and total time traveling was 7 hours.


Going to Granmother's ----- {{{60*u=d}}}
u is time and d is distance.  We know neither.
Also, {{{u=d/60}}}


Returning from Grandmother's----- {{{45*v=d}}}
v is time traveling and d is distance.  We know neither.
Also, {{{v=d/45}}}


...but we know that d is the same in each equation, being distance to grandmother's house.  


Use the time travel information give, that 7 hours.
{{{u+v=7}}}
{{{highlight(d/60+d/45=7)}}}
SOLVE for d.