24000 forints we borrow, and repay with 1500 forint annual arrears. From the fifth year onwards, we want to repay the remaining debt in equal annual arrears over 7 years. What will this annuity be if the loan accrues interest at 4.5%?

We have a loan of 24000 forints, which we repay with 1500 forint annual arrears. Starting from the fifth year, we want to repay the remaining debt in equal annual arrears over 7 years. What will this annuity be if the loan accrues interest at 4.5%?
If we denote the annuity by $r$ and the interest factor by $e$, then

$$
\left(24000 e^{5}-1500 \frac{e^{5}-1}{e-1}\right) e^{7}=r \frac{e^{7}-1}{e-1}
$$

from which $r=3682$ HUF.

(Tivadar Kerekes, Déva.)

The problem was also solved by: Benedek Zs., Filkorn J., Freibauer E., Kiss A., Krausz B., Krisztián Gy., Lindtner M., Lukhaub Gy., Rozlosnik P., Sasvári G., Weisz J.