That is exactly 8 half lives.
After 8 half - lives only (1 / 2^8) or (1 / 256) of the original 30 grams will remain.
(1 / 256) =
<span>
<span>
<span>
0.003906250
</span>
</span>
</span>
So, 30 * <span>
<span>
0.003906250 = </span></span>
<span>
<span>
<span>
0.1171875 grams will remain.
</span></span></span>
Let the unknown number be x.
x × -7 = 7 (x + -40)
-7x = 7x - 280
-14x = -280
x = 280/14
x = 20
Hope this helps!
$x=3$ I think that’s it... try that
Answer:
Step-by-step explanation: