Answer:
$17,922.55
Explanation:
The future value of a one-time investment is calculated using the formula ...
FV = P(1 +r/n)^(nt)
where principal P is invested at annual rate r compounded n times per year for t years.
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You have FV = 44000, r = 0.05, n = 12, t = 18, and you want to find P.
44000 = P(1 +0.05/12)^(12·18) ≈ 2.455008P
P = 44000/2.455008 = 17,922.55
The couple must deposit $17,922.55 in order to have $44,000 in 18 years.
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Additional comment
Some calculators, all spreadsheets, and a number of apps can make this calculation for you. All you must do is fill in the numbers.