Step 1: Read the two years from the graph.
From the line graph, sales in $2021$ are $40$ lakh and sales in $2025$ are $90$ lakh.
Step 2: Recall the growth formula.
Percentage increase compares the rise to the starting value. \[ \text{Increase}\% = \frac{\text{new} - \text{old}}{\text{old}} \times 100 \]
Step 3: Find the actual rise.
The rise is $90 - 40 = 50$ lakh.
Step 4: Compare against 2021.
Divide the rise by the $2021$ value, $\frac{50}{40}$.
Step 5: Convert to a percent.
$\frac{50}{40} \times 100 = 125$.
Step 6: State the answer.
Sales grew by $125\%$ from $2021$ to $2025$. \[ \boxed{125\%} \]