Answer:
Option D The solution of the system is the point (-3,5)
Step-by-step explanation:
we have
x+y=2 -----> equation A
y=-2x-1 ------> equation B
Solve the system by substitution
Substitute the equation B in equation A and solve for x
x+(-2x-1)=2
-x-1=2
x=-2-1
x=-3
Find the value of y
y=-2x-1
y=-2(-3)-1
y=5
therefore
The solution of the system is the point (-3,5)
Answer:

Step-by-step explanation:
- t = time (in hours) → this is the independent variable
- s = total area cleaned (in square feet) → this is the dependent variable (as the number of square feet cleaned depends on the number of hours worked)
Therefore, if the rate of cleaning is 8 1/4 square feet per hour, the relationship between s and t is:

Answer:
The probability is 
Step-by-step explanation:
We can divide the amount of favourable cases by the total amount of cases.
The total amount of cases is the total amount of ways to put 8 rooks on a chessboard. Since a chessboard has 64 squares, this number is the combinatorial number of 64 with 8,
For a favourable case, you need one rook on each column, and for each column the correspondent rook should be in a diferent row than the rest of the rooks. A favourable case can be represented by a bijective function
with A = {1,2,3,4,5,6,7,8}. f(i) = j represents that the rook located in the column i is located in the row j.
Thus, the total of favourable cases is equal to the total amount of bijective functions between a set of 8 elements. This amount is 8!, because we have 8 possibilities for the first column, 7 for the second one, 6 on the third one, and so on.
We can conclude that the probability for 8 rooks not being able to capture themselves is

0.5 because 50 is 1/2 of 100.