Stephanie has $152 in her bank account. she withdraws $20. then, she deposits $84. write an addition expression to represent this situation. then, find the sum and explain it's meaning.

Carbon- 14 is a radioactive form of carbon found in all living plants. after a plant dies, the carbon- 14 disintegrates. samples of similar living plants are used to determine the age of the remains. the amount of carbone-14 present after t years is given by the exponential equation n(t) = noe where no is the initial amount of carbon-14. the half-life of carbone-14 is 5600 years. charcoal from an ancient fire pit contains one third of earbon-14 found in similar living wood of the same size. find the age of the charcoal half-life is the time required for a quantity to reduce to half its initial amount