Answer:
42/50, 21/25
Step-by-step explanation:
84/100=42/50=21/25
Answer:
50
Step-by-step explanation:
must use PEMDAS (order of operations)
step 1: multiply 7 and 6
8 + 42 / 3 x 3
step 2: divide 42 by 3
8 + 14 x 3
step 3: multiply 14 and 3
8 + 42
Add to get 50
Answer:

Step-by-step explanation:




<em>Hope this helps!!!</em>
Answer:
216
Step-by-step explanation:
300 x .28 = 84
300 - 84 = 216
The half-life of Po is 139 days, so its decay rate is
0.5 = e^(139k) ==> k = ln(0.5)/139
After some time t, 80% of the material will have decayed and you'll be left with a sample 20% of its original mass:
0.2 = e^(kt) ==> t = ln(0.2)/k = ln(0.2)/ln(0.5) * 139 = 322.748
so your sample is usable for about 323 days.