(70 x 3.28) = feet per second
(70 x 3.28) ÷ 6,080 = nm per second
((70 x 3.28) ÷ 6,080) x 60 = nm per minute
((70 x 3.28) ÷ 6,080) x 60 x 60 = nm per hour (kts)
= 135.95 kts