Answer:
Eric's expression is :

and Andrea's is :

In Eric's expression, 20 represents the initial amount of substance with which he has started the experiment.
is the amount of substance left after each time period (in this case, each week).The variable w in this case represents the number of weeks.
Andrea's expression can be written as :

The one outside of parentheses represents the initial amount of the substance. The one inside of parentheses represents 100% of the original amount of the substance. 0.5 represents the 50% of the substance that is lost each time period. The variable w in this case represents the number of weeks.
Answer: -3
Since the both equal the same value we can combine the into -8x-2=-6x+4.
From there you can solve from whatever side you want, and the answer is -3.
I think it is 70 but not sure
Answer:
I solution; x=8
Step-by-step explanation:
You have to solve for x by simplifying both sides of the equation and then isolating the variable
3(x+2)= 2x+14
Distributive Property
3x+6=2x+14
Isolate the variable
3x+6-6=2x+14-6 which is 3x=2x+8
3x-2x=2x-2x+8
x=8