If triangles AMN and ABC are similar, then
AM/AB = AN/AC
or
AM/(AM + MB) = AN/(AN + NC)
Check if this is true:
AM/AB = 21/(21 + 9) = 21/30 = 7/10
AN/AC = 14/(14 + 6) = 14/20 = 7/10
The angle at vertex A is common to both of the triangles.
Then by the side-angle-side (SAS) similarity theorem, the triangles are indeed similar.

because it's a linear function.
Answer:
Option (c) is correct.
Step-by-step explanation:
Given equation is :

The equation can be solved for a as follows :
Step 1.
Cross multiply the given equation

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".