Answer:
Option (c) is correct.
Explanation:
Given equation is :
![s=(a+b+c)/(3)](https://img.qammunity.org/2021/formulas/mathematics/high-school/hvomg1ayaedlxng8sdz58aoab9cluy3qzx.png)
The equation can be solved for a as follows :
Step 1.
Cross multiply the given equation
![3s=a+b+c](https://img.qammunity.org/2021/formulas/mathematics/high-school/p76067jnjvo6ui8j8ut7qb7j0lwjow3e1i.png)
Step 2.
Now subtract b on both sides
3s-b = a+b+c-b
3s-b = a+c
Step 3.
Subtract c on both sides
3s-b-c=a+c-c
⇒ a=3s-b-c
The statement that is true for Darpana is " In step 3, she needed to subtract c rather than divide".