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:
The two major events that helped bring about the Renaissance were the Black Death and the development of banking systems
Step-by-step explanation:
To get this percentage, divide costs by total food sales
2250 / 25000 = 0.09
then multiply by 100 to get the % = 9%
Step-by-step explanation:
Sum of arithmetic terms = n/2 × [2a + (n - 1)×d], where 'a' is the first term, 'd' is the common difference between two numbers, and 'n' is the number of terms.
this is the same as n/2 × (a1 + an), because
an = a1 + (n-1)×d
so, for the series above :
a or a1 = 2
d = 7, as every new term is the previous term plus 7.
for n
37 = a1 + (n-1)×d = 2 + (n-1)×7
and now solve for n
35 = 7n - 7
42 = 7n
n = 6
so, the sum of all terms is
6/2 × (2+37) = 3×39 = 117
