Answer:
12
Step-by-step explanation:
x = number of $1 bills
y = number of $5 bills
z = number of $10 bills
We know that:
x + y + z = 25 (total amount of bills)
x + 5y + 10z = 100 (total amount of money)
y = 4z (Given)
Substitute the third equation into the first one.
x + 4z + z = 25
x = 25 - 5z
Put this into the second equation.
(25 - 5z) + 5 (4z) + 10z = 100
Simplify and solve.
25 - 5z + 20z + 10z = 100
25z + 25 = 100
25z = 75
z = 3
Substitute this into y = 4z
y = 4 * 3
y = 12
So, there are 12 $5 bills.
Answer:
12 $5 bills
Step-by-step explanation:
Represent the number of each kind of bill by x, y and z: there are x $1 bills, y $5 bills and z $10 bills.
According to the problem statement,
x + y + z = 25 and y = 4z (or z = y/4). Also, the values of the bills add up to $100:
($1)x + ($5)y + ($10)z = $100. Eliminate z by typing y/4 in its place:
x + y + (y/4) = 25 and
x + 5y + 10(y/4) = 100
Doing this has reduced the number of variables to two: x and y. Combining like terms in both equations, we get:
1x + (5/4)y = 25 and
1x + (30/4)y =100
Subtracting the 1st equation from the 2nd, we get:
(25/4)y = 75, or
(4/25)(25/4)y = (4/25)(75) , or y = 12.
If y = 12, z = 12/4, or 3.
Then x + 12 + 3 = 25 coins in all; therefore, x = 15 = 25, and x = 10
There are 10-$1 bills, 12-$5 bills and 3-$10 bills.
