You are "missing" a critical piece of information, namely: the frequency of payment. However, that is implied in the last word: "monthly".
In that case, the parameters must be in units of months. So "rate" is typically 9%/12, and "nper" is 5*12.
(Not to over-complicate things, but monthly "rate" is sometimes calculated differently in some countries for some types of loans, notably mortgages. Let us know if your results do not match the answer that might be given in your text. In that case, let us know what answer is given so that we reverse-engineer the monthly rate calculation.)
Also note that CUMPRINC differs from most Excel financial functions insofar as the "pv" parameter __must_be__ positive. Consequently, CUMPRINC returns a negative value. If you want it to be positive (typically), simply write =-CUMPRINC(...). Note the unary minus in front.
For most loans, "type" is zero (payment at the end of the period).
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It is odd that the question asks you to use CUMPRINC per se to calculate __interest__. Usually, we would use CUMIPMT.
If you are sure that the question requires that you use CUMPRINC [sic], you will need to calculate the monthly payment using the PMT function.
To make that simple, you can use the same parameters for "rate", "nper" and "pv". But again, note that PMT will return a negative value. The "fv" and "type" parameters can be omitted; or you can enter zero.
Mathematically, the total interest paid in "n" periods is n*payment - cumPrincipal, treating each value as positive. Taking into account that PMT and CUMPRINC return negative values, we would write:
=-(18-10+1)*PMT(...) + CUMPRINC(...)
Of course, you can substitute 9 for (18-10+1). But typically, 10 and 18 are replaced with cell references so that they can be variable.
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Odd that the question says ``paid in the second Year [sic] of payments, for periods 10 through 18``.
A year being 12 months, usually periods #10-12 are in the __first__ "year" (but not necessarily calendar year) and periods #13-18 are in the __second__ "year".
And the total of periods #10-18 comprise 9 months, not a whole(?) "year" (12 months) or even the number of payments in the second calendar(?) year.
Double-check your reading of the question for any possible misunderstandings.