I think the problem is simple interest the principal is separated from the interest.

first, P 25 000 is subtracted to P 10 000 and you'll get P 15 000

then your final principal is P 15 000

then get the simple interest:

P = P 15 000

R = 14 %

T = 4 months

then use the formula for finding the simple interest:

Simple interest = principal x rate x time or S = p x r x t

substitute:

Simple interest = P 15 000 x 0.14 x 4 =

simple interest = P 8 400

so, Mrs. Gillera pay P8 400 in the last payment.

how many times she pay ?

so divide P 25 000 to the simple interest and you'll get 3.

therefore, Mrs. Gillera pay 3 times.