Question:

Laura, a bond portfolio manager, administers a $10 million portfolio. The portfolio currently has a duration of 8.5 years. Laura wants to shorten the duration to 6 years using T-bill futures. T-bill futures have a duration of 0.25 years and are trading at $975 (face value = $1,000). How is this accomplished?

Please explain and do not copy from Chegg. Otherwise i have to report the answer.