R pays Rs 100 to P with Rs 5, Rs 2 and Rs 1 coins. The total number of coins used for paying are 40. What is the number of coins of denomination Rs 5 in the payment?

Options
a) 18
b) 16
c) 17
d) 13

Solution

As per question
R pays to P = 100 Rs.
R gives coins to P = 5 , 2 , 1
No. of coins = 40
5x + 2y + 1z = 100
x + y + z = 40
Solve the both equations
4x – y = 60
x is the no. coins which cannot be negative
So that value of x will be 15 or less, in the option less than 15 is only 13.
So the answer is 13

Anser: d) 13