I believe you are referring to the half-life formula, which is used to calculate the half-life (when the substance drops to half of its original amount) of radioactive substances. The equation is as follows:

<em>A</em> is the remaining amount
<em>P</em> is the initial amount
<em>t</em> is the time that has passed
<em>h</em> is the half-life of the substance
When plugging values into the equation, make sure that <em>t </em>and <em>h </em>are both measured in the same unit (e.g. <em>t </em>days and <em>h </em>days), as well as <em>A </em>and <em>P</em>.
Supplementary Angles:

Arithmetically speaking, the closest 2 supplementary angles can get (in 3 and 2 digits respectively) is the upwritten.
Complementary Angles:

Simply, in this case, for angles to be numerically as close as possible - make both the angles 45°.
we know that
If a ordered pair (x,y) is a solution of the equation, then the ordered pair must satisfy the equation
we have the equation

Let's verify all the cases to determine the solution to the problem.
<u>case A)</u> point 
Substitute the values of x and y in the equation



-------> is true
therefore
The point
is a solution of the equation
<u>case B)</u> point 
Substitute the values of x and y in the equation



-------> is true
therefore
The point
is a solution of the equation
<u>case C)</u> point 
Substitute the values of x and y in the equation



-------> is not true
therefore
The point
is not a solution of the equation
<u>case D)</u> point 
Substitute the values of x and y in the equation



-------> is not true
therefore
The point
is not a solution of the equation
therefore
<u>the answer is </u>

