No excel. Matteo Toys has $8\mathrm{.}5\%$ annual coupon, $$1,000$ face value bonds outstanding that mature in $10$ years. However, the bonds can be called before maturity at a call price of $$1,042\mathrm{.}5.$ The bonds have a yield to call of $7\mathrm{.}5\%$ and a yield to maturity of $7\mathrm{.}85\%.$ How long until these bonds may first be called?