Question

A girl can cycle at 16 km/h and walk at 7 km/h. To cover a distance of 109 km, she takes 8.5 hours. How much distance did she cover on foot ?

Answer 1

$let \: x = timetaken \: to \: travel \: on \: foot \\ y = timetaken \: on \: cycle \\ total \: distance \: d = 109km \\ x + y = 8.5 \\ 109 = 7x + 16y \\ on \: solving \: both \: eqns \: x = 3hr \: y = 5.5 \\ distance \: traveled \: on \: foot = 3hr \times 7kmph \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 21km$