Question

Gerardo changed a $100 at the bank. He received $20 bills and $10 bills.

$20 bills was 2 more than the number of $10 bills. How many bills of each kind did he
receive?
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Answer 1

• Two $10 bills

• Four $20 bills

Explanation:

We are told that Gerardo received a number of $20 and $10 bills upon changing a $100 bill at the bank. We are also told that he received 2 more $20 bills than $10. Then we are asked to find the number of each kind of bill.

To solve this problem, let's consider the number of $10 bills he received was
`x`. Since he received 2 more $20 bills, he got
`(2 + x)` $20 bills. Therefore, in total he received:

`10 * x + 20 * (x +2)`

This should add up to $100 since that is the amount he changed. Solving the resulting equation for
`x` will give us the number of $10 bills he received.

`10 * x + 20 * (x +2) = 100`

⇒
`10x + 20x + 40 = 100`

⇒
`30x +40 = 100`

⇒
`30x + 40 - 40 = 100 - 40` [Subtracting 40 from both sides of equation]

⇒
`30x = 60`

⇒
`(30)/(30)x = (60)/(30)` [Dividing both sides of the equation by 30]

⇒
`x = \bf 2`

Therefore, he received 2 $10 bills.

Since the number of $20 bills is 2 more than the number of $10 bills,

no. of $20 bills = 2 + 2

= 4