-4 times -1 +(-3) need ASAP plz

Multiply

Note: Multiply a negative to a negative will equal a positive.

Add

the ratios are reciprocals im positive

step-by-step explanation:

they are all positive numbers so it wouldn't be the other ones

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

source: