A Family Planning Weekend Trip

Farthest distance from home they can plan to go is

Distance Travelled = Speed * Time  => 40 x = 30 (8-x)

x = 24/7

So Max Distance they can travel  = 40 * 24/7 = 137.14

  

Here 1 km = 0.625 miles (approximately)
40 miles = 40 * 1/0.625 kms/hr = 64 kms/hr
30 miles = 30 * 1/0.625 kms/hr = 48 kms/hr
h= time taken to travel destination
Distance travelled till destination = 64 * h
Distance travelled from destination till home = 48 * (8-h)
as the distance travelled from home to destination & vice-versa is same
64 * h = 48 * (8 - h)
h = 24/7

Distance travelled till destinace(Far distance travelled from home) = 64 * 24/7 = 219.43 kms = 137.15 miles (approximately)

137.5mile