Answer: 20 of banknotes, denomination of Rs. 10 and 15 of banknotes, denomination of Rs. 20.
Step-by-step explanation:
Let the number of banknotes, denomination of Rs. 10 will be equal to x,
and the number of banknotes, denomination of Rs. 20 will be equal to y.
Hence; [tex]\left \{ {{x+y=35\ \ \ \ } \atop {10*x+20*y=500\ |:10 \ \ }} \right. \ \ \ \ \left \{ {{x+y=35\ \ (1)} \atop {x+2y=50\ \ (2)}} \right. \\[/tex]
From (2) subtract (1):
[tex]y=15\ \ \ \ \ \Rightarrow\\x+15=35\\x=20.[/tex]