A force $\left(\overrightarrow{\mathrm{F}}\right) = 3\overbrace{\mathrm{i}}+\mathrm{c}\overbrace{\mathrm{j}}+2\overbrace{\mathrm{k}} \mathrm{acting} \mathrm{on} \mathrm{a} \mathrm{particle} \mathrm{causes} \mathrm{a} \mathrm{displacement}: \left(\overrightarrow{\mathrm{s}}\right) = -4\overbrace{\mathrm{i}}+2\overbrace{\mathrm{j}}+3\overbrace{\mathrm{k}}$ in its own direction. If the work done is 6 J, then the value of ‘c’ is