This is how I tried it,

$x=4\mathrm{cos}(t)\to dx=-4\mathrm{sin}(t)$

$y=3\mathrm{sin}(t)\to dy=3\mathrm{cos}(t)$

and $0\le t\le 2\pi $

${\int}_{C}F.dr=\int -ydx+xdy={\int}_{t=0}^{2\pi}12({\mathrm{sin}}^{2}(t)+{\mathrm{cos}}^{2}(t))dt=75.4$

But answer given to me at the back is 98.2 and doesn't agrees with mine.