Question

A purse contains some Rs 5 and Rs 10 coins.if the total numbers of these coins is 20 and the total value of these coins isRs 165.Find the number of 10 rupee coins in the purse

Answer 1

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

Answer 2

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