The equation of trajectory of a projectile is $\mathrm{y}=10\mathrm{x}-\left(\frac{5}{9}\right){\mathrm{x}}^2.$  if we assume $\mathrm{g}=10{\mathrm{ms}}^{-2}$  the range of projectile (in meters) is

$$\begin{gathered} given y=10x-\frac{5}{9}{x}^2 \\ comparing with general equation of projectile \\ \Rightarrow y=Ax-B{x}^2\text{\hspace{0.17em} or y=x tanθ(1-}\frac{x}{R}\text{)} \\ y= 10x (1-\frac{1}{18}) \\ Range=18m \end{gathered}$$