Answer: $12,113.14
Explanation:
Find out the future value of each payment 20 years from now then sum up the values.
Year 1:
= 250 * ( 1 + 15%)¹⁹
= $3,557.94
Year 2:
= 300 * ( 1 + 15%)¹⁸
= $3,712.636
Year 3:
= 450 * ( 1 + 15%)¹⁷
= $4,842.5688
Future value of all:
= 3,557.94 + 3,712.636 + 4,842.5688
= $12,113.14