Question 772078
Assuming your "10 mmm" is misprint for "10 km", this data table shows the information.


_______________(km/hour)______(hours)__________(km)
ROAD___________rate___________time_____________distance
Gravel_________40_____________g________________40*g
City___________60_____________c________________60*c
Total_________________________2________________110


Variables are assigned as g for travel time on gravel and c for travel time in the city.

Two equations come from the data:
{{{highlight(g+c=2)}}} and {{{highlight(40g+60c=110)}}}


WHAT TO DO:
Solve the system for g and c, and use pick the expression for the distance which you want computed and compute it.  That would be the 60*c number.