39
Subtraction is fundamentally distance on a number line. A distance of 5 from 55 to 60, then a distance of 30 from 60 to 90, then a distance of 4 from 90 to 94. Total distance = 5 + 30 + 4 = 39. --- Alternately, the distance from 54 to 94 must be 40, so the distance from 55 to 94 must be one less, a distance of 39.