Question

A cashier has 30 bills, all of which are $10 or $20 bills. The total value of the money is $460. How many of each type of bill does the cashier have?

Answer 1

the cashier has 16 $10 bills and 14 $20 bills
16×20=320
14×10=140
320+140=460

Answer 2

There are 14 $10 bills and 16 $20 bills.

Explanation:

Let

x = number of $10 bills

y = number of $20 bills

The sum of the value of x and y is $460.

10 x + 20 y = 460 [1]

The sum of x and y is equal to the total number of bills.

x + y = 30

y = 30 - x [2]

We replace [2] in [1],

10 x + 20 (30 - x) = 460

10 x + 600 - 20 x = 460

-10 x = -140

x = 14

We can get y if we replace this value of x in [2].

y = 30 - 14 = 16