No, it isn't!
first, the discount is 20 percent of 18 dollars, that is 18/5=3.6
this means that during the first week the prize is 18-3.6=14.4
now, the prize is marked up 20 % of 14.4! this is 2.88
so the prize later will be 14.4+2.88, that is 17.28, not 18
what is relevant here is what a number is a percent OF
If 
is the amount of strontium-90 present in the area in year 
, and it decays at a rate of 2.5% per year, then
Let 
be the starting amount immediately after the nuclear reactor explodes. Then
or simply
So that after 50 years, the amount of strontium-90 that remains is approximately
or about 28% of the original amount.
We can confirm this another way; recall the exponential decay formula,
where is measured in years. We're told that 2.5% of the starting amount 
decays after 1 year, so that
Then after 50 years, we have
Answer:
19/20 is the correct answer
Answer:
7 3/25
Step-by-step explanation:
Answer:
20x + 13
Step-by-step explanation:
5(4x + 3) - 2
5× 4x + 5×3 - 2
20x + 15 - 2
20x + 13
