Answer:
Present value = FV / (1 + r)^t
1. PV = $19,415 / (1 + 0.07)^15
PV = $19,415 / (1.07)^15
PV = $19,415 / 2.759031
PV = $7,036.89
2. PV = $47,382 / (1 + 0.11)^8
PV = $47,382 / (1.11)^8
PV = $47,382 / 2.3045378
PV = $20,560.31
3. PV = $312,176 / (1 + 0.10)^13
PV = $312,176 / (1.10)^13
PV = $312,176 / 3.4522712
PV = $90,426.27
4. PV = $629,381 / (1 + 0.13)^25
PV = $629,381 / (1.13)^25
PV = $629,381 / 21.230542
PV = $29,645.07