Let X=Number of 1 Rupee coins
Y= Number of 2 Rupee coins
Z= Number of 5 Rupee coins
Given,Number of coins ( X + Y + Z ) =300$\cdots$(1)
1 X + 2 Y + 5 Z=960$\cdots$(2)
Number of 1 Rupee coins and the number of 2 Rupess coins are interchenged.So,
2 X + Y + 5 Z = 960 - 40 = 920 $\cdots$(3)
From (1) ,(2) and (3)
Y - X = 40$\cdots$(4)
Y + 4 Z = 660$\cdots$(5)
X + 4 Z = 620$\cdots$(6)
Put the value of X and Y from (5) and (6) in (1)
620 - 4 Z - 660 - 4 Z + Z = 300
Z = 140
Hence,Option (2)140 is the correct choice.