Please help i can’t figure out which answer it is.

45

Step-by-step explanation:

So you have the equation:

(3x - 5) ^(x) - 19

and the value x = 3,

so just substitute in and simplify:

(3*3 - 5) ^ (3) - 19

(9 - 5)^(3) - 19

(4)^(3) - 19

64 - 19

45

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: