The longest side
Think about it. The widest angle would leave a resulting long side to reach the ends of the angle
If you look at the picture, the side across from the widest angle has the longest length
I think it is 78 I hope is help you :)
Answer:

Step-by-step explanation:
Given



Required
Her salary in that month
Given that she spent
of her salary on shopping, this implies that she has
of her salary left
From what's left, she gave her sister 
This means she gave her sister 
Sister = 
Calculating a fraction of what's left




Recall that she has Rs11,040
This means that

Multiply both sides by 




Hence, her salary for that month was Rs23000