Arturo O. answered • 05/28/16

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v = speed of flight if no wind

u = wind speed = 8 mph

t = flight time against wind

t - 16 = flight time with help from wind

d = distance = 4161 miles

Outbound:

(v - 8) * t = 4161 [equation 1]

Inbound:

(v + 8)(t - 16) = 4161 [equation 2]

Subtract equation 2 from equation 1 and get

(v - 8) * t - (v + 8)(t - 16) = 0

vt -8t -(vt -16v +8t -128) = 0

t(v - 8 - v - 8) - (-16v- 128) = 0

-16t = -(16v + 128)

t = v + 8

Substitute this result for t into equation 1 and get

(v - 8) * (v + 8) = 4161

v^2 - 64 = 4161

v = sqrt(4225) = 65 mph

t = v + 8 = 65 + 8 = 73 hrs