For each $$1,000$ face value of the $10\mathrm{.}625\%$ bond, how much to go long and how much

of the $4\mathrm{.}25\%$ to go short to construct a portfolio that was neutral to interest rate changes?

$$ PV$0110\mathrm{.}625\%=0\mathrm{.}0741$; PV$014\mathrm{.}25\%=0\mathrm{.}0625$

$$ Market price of $10\mathrm{.}625\%$ bond $=141\mathrm{.}8281$ plus accrued interest of $$23\mathrm{.}68$

$$ Market price of $4\mathrm{.}25\%$ bond $=105\mathrm{.}9688$ plus accrued interest of $$0\mathrm{.}947$