Which of the following are sources of electromagnetic radiation on Earth?
It's in the doc below

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:  

ιт ωιℓℓ вєтнє fιяѕт ¢нσι¢є(α.)

convert the exponential equation to a logarithmic equation using the logarithm base (6) of the right side (36) equals the exponent (2).

ℓσg6(36)=2

нσρє ι ¢συℓ∂ нєℓρ уα