a man borrows rs.1000 and agrees to repay it with a total interest of rs.140 in 12 installments,each installment being less than the one preceding it by rs. 10. what shoukd be his first installment.

suppose x is the initial installment so the next will b x-10,x-20, x-30 and so on upto x-110 and the total amt paid will be 1000+140=1140 so (x+x-10+x-20+x-30+........x-110) =1140 12x-660=1140 12x=1800 x=150