The fact family model represents 6 + 5 = 11.

A triangle. 11 is in the top corner. 6 is in the bottom left corner. 5 is in the bottom right corner.
How does 11 compare to 6?

11 less than 5 is 6.
11 more than 5 is 6.
6 is 5 less than 11.
6 is 5 more than 11.

5: 20

step-by-step explanation:

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:  

answer is 270 degrees: -

to convert radians to degrees you multiply by 180/π

9π/ 6 * 180 / π

=   9 * 180 / 6

= 9 * 30

=   270 degrees   answer