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>.
Answer: Brian gets $39.2 more over Colin.
Step-by-step explanation:
Given: Total tip amount = £78.40
The ratio of the share of tips for Pawl, Colin and Bria is 2:1 :5.
Let tip amount for Pawl = 2x, tip amount for Colin = x , tip amount for Bria = 5x
Then, 2x+x+5x= 78.40

Tip for Colin = $ 9.8 , Tip for Bria = 5($9.8)= $49
Difference = $(49-9.8) = $ 39.2
Hence, Brian gets $39.2 more over Colin.
Answer:
3- (-5) + -2.
Step-by-step explanation:
Anything plus a negative number will either make that negative number go closer to zero, or turn into a positive number.