Answer:
Theresa has 8 $5 bills and 10 $1 bills.
Explanation:
Guess and Check Method
Start by guessing how many $5 bills Theresa has: 10.
Calculate how much money she has from $5 bills: 10 * $5 = $50.
Calculate how many $1 bills she has: 18 - 10 = 8.
Calculate how much money she has from $1 bills: 8 * $1 = $8.
Check to see if her total amount of money is equal to $50: $50 + $8 = $58.
Since her total amount of money is not equal to $50, our guess was incorrect.
Repeat steps 1-6, trying different numbers of $5 bills until you find a combination that results in a total of $50.
Correct Answer: Theresa has 8 $5 bills and 10 $1 bills.
Check:
$5 bills: 8 * $5 = $40
$1 bills: 10 * $1 = $10
Total: $40 + $10 = $50