Question

"A cash drawer contains 29 bills, all twenties and fifties. If the total value of the bills is $820, how many twenties and how many fifties are in the drawer?"

Answer 1

Answer:there are 21 twenties and 8 fifties in the drawer.

Explanation:

Let x represent the number of bills that are twenties in the drawer.

Let y represent the number of bills that are fifties in the drawer.

The cash drawer contains 29 bills. All twenties and fifties. This means that

x + y = 29

If the total value of the bills is $820, it means that

20x + 50y = 820 - - - - - - - - - - 1

Substituting x = 29 - y

20(29 - y) + 50y = 820

580 - 20y + 50y = 820

- 20y + 50y = 820 - 580

30y = 240

y = 240/30 = 8

x = 29 - y = 29 - 8

x = 21

Answer 2

There are 21 twenties and 8 fifties in the drawer.

Explanation:

This question can be solved by a system of equations.

I am going to say that:

x is the number of twenties

y is the number of fifties.

A cash drawer contains 29 bills.

This means that x + y = 29.

The total value of the bills is $820.

This means that 20x + 50y = 820.

So

x + y = 29

20x + 50y = 820

From the first equation, x = 29 - y. So:

20x + 50y = 820

20(29 - y) + 50y = 820

580 - 20y + 50y = 820

30y = 240

y = 8

And

x = 29 - y = 29 - 8 = 21

There are 21 twenties and 8 fifties.