Ratio of number of coins,
1Rs : 50p : 25p = 7 : 8 : 9
Let the total value of 1Rs coin is =7x×1=7x
Total Value of 50p coin =8x×21=28x=4x
Total Value of 25p coin =9x×41=49x
Total Amount =7x+4x+49x=159
=>\frac{28x+16x+9x}{4}=159
=>53x=159\times{4}
=>x=3\times{4}
=>x=12
No. of 50p coins =8x=8×12=96