A cash register contains only five dollar and twenty dollar bills. It contains three times as many five dollar bills as twenty dollar bills and the total amount of money in the cash register is $735. How many five dollar bills are in the cash register?

Question

anonymous · Answer

Let x=number of $5, y= number of $20
5x+20y=735

anonymous · Answer

Let x be how many $20s you have in the register

Then you can set up the equation as such

$$3x($5) + x($20) = 735$$

Solve for x and that will give you how many $20s you have in your reg.  Then using that, multiply "x" by 3 to find out how many $5s you have (since you have 3 times as many five dollar bills as twenty)

anonymous · Answer

Let x=number of $5, y= number of $20
5x+20y=735
x=3y
5(3y)+20y=735
Use substitution to solve.

anonymous · Answer

when you do that, you get x=63 and y=21

anonymous · Answer

so there are 63 five dollar bills