Find measure of arc or angle indicated

but there’s no any figure there!

it has to have an angle of 90 degrees

why are you giving so many marks make your marks less and make a question list so that i can understand your question very nicely

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

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