I just finished this test and the correct answer is "4x + 6y < 120" or "B"
To solve this we are going to use the half life equation

Where:

is the initial sample

is the time in years

is the half life of the substance

is the remainder quantity after

years
From the problem we know that:



Lets replace those values in our equation to find

:




We can conclude that after 1600 years of radioactive decay, the mass of the 100-gram sample will be
91.7 grams.
Answer
-8, -7, -2, 3, 5
Explanation
Positive numbers go up as they increase.
Negative numbers go up as they decrease.
It's suppose to be -18 so I guess no real number....