For this case we have an equation of the form:
 y = A (b) ^ x
 Where,
 A: initial amount
 b: growth rate
 x: time
 Substituting we have:
 y = 6 * (2) ^ (x-1)
 For year 5 we have:
 y = 6 * (2) ^ (5-1)
 y = 96
 Answer:
 by the end of the 5th year Paul's company build:
 A.) 96
