QM
posted by chan .
I have borrowed a sum of $150000 for buying house at 12% simple interest per year at the beginning of a year.The loan has to be repaid by three payment of $10000,$30000 and $X at the end of February, July and November of the same yaer respectively. Find $X.

I would make three calculations. The math guys probably have a formula that works it all at once.
First payment is 10,000.
Interest for Jan and Feb = 2 months
150,000 x 0.12 x (2/12) = 3,000 interest and we pay 10,000.
Net loan at end of Feb is 150,000+300010,000 = 143,000
Continue in this style to find the last payment.