Answer: $42042.50
Explanation:
We need to use algebra and equations.
A = P x (1 + (R/n)/100)^nt
our amount (A) is $72K
the number of times we compound the money (n) is 12 (12 months in a year, 'compounded monthly')
our rate (R) is 9 (9%)
our time (t) is 6 (6 years)
we need to find our principal/initial amount (p)
72000 = p x (1 + 0.0075)^12x6
p = $42042.50