$$\begin{aligned} y=x^2-5 x, y=7 x-x^2 & \Rightarrow \quad x^2-5 x=7 x-x^2 \\ & \Rightarrow \quad x=0, x=6 \end{aligned}$$

$$\text { Area }=\int_\limits0^6\left[\left(7 x-x^2\right)-(x-5 x)\right] d x$$

$$=\int_\limits0^6\left(12 x-2 x^2\right) d x=6 x-\left.\frac{2 x^3}{3}\right|_0 ^6$$

$$=216-144=72 \text { sq. unit }$$

But answer is 198 as per NTA.