Answer:
10,000 * (0.5)^x/19 ; 19.53125
Step-by-step explanation:
Sorry, Im not good at chemistry, but I think this is how you do it.
Part 1: 10,000 * (0.5)^x/19 x=time
Part 2: 10,000 * (0.5)^171/19 = 10,000 *(0.5)^9 = 19.53125
