Duration 125, addition, overnight, agreement, why

LPoulin133

Can someone explain why you have $100M in denominator, and not $125M? This is question 14 on page 151in CFAI.

" if we use funds from a $25 million overnight repo agreement to purchase bonds in addition to the current $100 million portfolio, the levered portfolio’s change in value for a 1% change in interest rates would equal $5,125,000 while giving you the portfolio duration you require."