Answer:

Step-by-step explanation:
we are given half-life of PO-210 and the initial mass
we want to figure out the remaining mass <u>after</u><u> </u><u>4</u><u>2</u><u>0</u><u> </u><u>days</u><u> </u>
in order to solve so we can consider the half-life formula given by

where:
- f(t) is the remaining quantity of a substance after time t has elapsed.
- a is the initial quantity of this substance.
- T is the half-life
since it halves every 140 days our T is 140 and t is 420. as the initial mass of the sample is 5 our a is 5
thus substitute:

reduce fraction:

By using calculator we acquire:

hence, the remaining sample after 420 days is 0.625 kg
1 cup = 8 fluid oz
8 × 8 = 64
So Joshua drinks 64 fluid ounces a day
Hope this helped. Have a great day!
Answer:
A and C
Step-by-step explanation:
-3*3 = -9
-1*-9 = 9
-27/3 = -9
-9/-1 = 9