1. At an annual effective interest rate of i, i > 0%, the present value of a perpetuity paying $10 at the end of each 3-year period, with the first payment at the end of year 3, is $40.

   At the same annual effective rate of i, the present value of a perpetuity paying $20 at the end of each 3-month period, with the first payment at 3 months, is X.

   Calculate X.