SOLUTION: Hello, I am trying to help my daughter with a math question that she doesn't understand. She lives in another state and gave me the problem over the phone. Math is one of my weak

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Question 126326: Hello,
I am trying to help my daughter with a math question that she doesn't understand. She lives in another state and gave me the problem over the phone. Math is one of my weaker subjects and her stepfather (who usually helps her) is out of town. The problem she gave me is as follows:
carbon 14 has 1/2 life of 5,730 years. after 17,190 years 1/8th of carbon 14 in a sample will be left. if 5 grams of carbon 14 are left after 17,190 years how much was in the original sample?
She said she is working on fraction equations.

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the amount of carbon you had in the first place. You know two things, the amount of carbon remaining is 1/8 of what you started with or x%2F8 and the amount of carbon remaining is 5 grams.

So x%2F8=5

Multiply both sides by 8
x=40