Question 311292
Let the number of $5 bills = x
And the number of $10 bills = y
Total nomber of bills x+y = 12   ...(1)
Total value is     5x+10y = 100  ...(2)
(1)*5=>            5x+5y =  60   ...(3)
(2)-(3)=>    5y=40
              y= 40/5
              y= 8
(1)=> x+8=12
x=12-8
x=4
So, the number of $5 bills = 4
And the number of $10 bills = 8