A wave on a string is described by

D$($x$,$t$)=(2\mathrm{.}8$cm$)$sin$[2$$($x$/(8\mathrm{.}4$m$)+$t$/(0\mathrm{.}14$s$)+1)],$ where x is in m and t is in s$.$ At t$=0\mathrm{.}49$s$,$ what is the displacement of the string at x$=4\mathrm{.}9$m$?$