And show work you if you answer i need this asap

1st Triangle ~ Scalene (no equal sides) [don't know why that was so hard]

2nd Triangle ~ Equilateral (all sides are equal) [once again...how was that hard?]

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: