Answers

2015-05-07T18:26:11+05:30
Let the no. of rs5 coin= x
          no. of Rs10 coin= 20-x
now
5x + 10(20-x)= 165
5x + 200 - 10x = 165
-5x = -35 (taking 200 to RHS)
 x=7
 therefore  RS 5 coins =7
                RS10 coins= 20-7=13

2 5 2
2015-05-08T10:52:25+05:30
Let 5 rp coins = x
so 10 rp coins = 20-x
now
5*x + 10 (20-x) = 165
5x + 200 -10x = 165
-5x = -35
x = 7

5 rp coins = 7
10 rp coins = 13
1 5 1