Help!! Radioactive iodine is used to determine the health of thyroid gland. It decays according to the equation y=ae^-0.0856t, where t is in days. Find the one-third life of this substance. Round to the nearest integer.
6
13
16
67

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.

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