(a) $x = (u\cos{\theta)t = 6t}$
$y = (u\sin{\theta)\ t - \frac{1}{2}{gt}^{2} = 8t - {5t}^{2}}$
$Therefore,\ \ \ u\sin{\theta = 8}$
$u\cos{\theta = 6}$
$Range.\ \ R = \frac{u^{2}2\sin{2\theta}}{g}$
$= \frac{u^{2} \times 2\sin{\theta\cos\theta}}{g}$
$= \frac{2(u\sin{\theta)\ (\cos{\theta)}}}{g}$
$= \frac{2(8)(6)}{10} = 9.6\ m$