Answer:
$134217728
Step-by-step explanation:
Day 1: $1
Day 2: $2
Day 3: $4
Day 4: $8
Day 5: $16
Day 6: $32
Day 7: $64
Day 8: $128
Day 9: $256
Day 10: $512
Day 11: $1024
Day 12: $2048
Day 13: $4096
Day 14: $8192
Day 15: $16384
Day 16: $32768
Day 17: $65536
Day 18: $131072
Day 19: $262144
Day 20: $524288
Day 21: $1048576
Day 22: $2097152
Day 23: $4194304
Day 24: $8388608
Day 25: $16777216
Day 26: $33554432
Day 27: $67108864
Day 28: $134217728