Determine the Present Value of the 7 annual cash payments. They must total $25,000. First get the PV of the amounts due in the first 3 yrs, at 8% - $2,315 + 4,287 + 5,954 = 12,556. That leaves 12,444, which is the PV of the 4 equal payments due in Yr 4 - 7. Next get the PV of 12,444 at T3, which is 15,676. Solve for the Annuity amount, at 8%, over 4 yrs, whose PV is 15,676. That is 4,733, or X in your problem.

still don't know how I can get this number 15,676.

how to get it with financial calculator?