Aman arranges to pay a debt of $90000 in 40 monthly instalments which are in A.P. when 30 instalments are paid, he dies leaving one third of the debt unpaid. Find the value of the first three instalments.

Juhi wants to buy a bicycle. She goes to the market and finds that the bicycle she likes is available for ₹1800. Juhi has ₹ 600 with her. So, she tells the shopkeeper that she would not be able to buy it. The shopkeeper, after a bit of calculation, makes the following offer. He tells Juhi that she could take the bicycle by making a payment of ₹600 cash down and the remaining money could be made in two monthly instalments of ₹610 each. Juhi has two options one is to go for instalment scheme or to make cash payment by taking loan from a bank which is available at the rale of 10% per annum simple interest. Which option is more economical to her?