Let the speed of the train be $x \text{km/h}$, time be $t \text{hours}$, and the distance be $d \text{km}$ $$d = x \times t \quad \text{(i)}$$ Case 1: Speed is $x + 10 \text{km/h}$ and time is $t – 2 \text{hours}$ $$-2x + 10t = 20 \quad \text{(ii)}$$ Case 2: Speed is $x – 10 \text{km/h}$ and time is $t + 3 \text{hours}$ $$3x – 10t = 30 \quad \text{(iii)}$$ Adding equations (ii) and (iii) to solve for $x$ $$x = 50 \text{km/h}$$ Substituting the value of $x$ into equation (ii) to find $t$ $$10t = 120 \Rightarrow t = 12 \text{hours}$$ Substituting the value of $t$ and $x$ into equation (i) to find $d$ $$d = 12 \times 50 = 600 \text{Km}$$ Hence, the distance covered by the train is 600km.