So, at the beginning there are a total of 25*3=75 siblings (we can assume that each of them had exactly 3 siblings, that's what average means; that we can assume this).
Now we have 25+1=26 students and the number of siblings is 75+8=83
and the average is
, and rounded it's 3.19.
Answer:
-The equation r+b-33 represents the total number of marbles
-There 9 black marbles
-There are 24 red marbles
Step-by-step explanation:
The bag contains 33 red and black marbles. Let the number of black marbles be b and that of red marble to r
Total number of marbles will be
b+r = 33 i.e b+r-33 = 0... (1)
If the number of red marbles is 6 more than double the number of black marbles, this can be represented as;
r = 6+ 2b... (2)
Substituting 2 in eqn 1 we have;
b + 6+2b = 33
3b = 27
b = 9
r = 33-9
r = 24
This shows that there are 9 black marbles, 24 red marbles and the equation r+b-33 represents the total number of marbles in the bag.
Answer:the third option is correct
Step-by-step explanation:
The system of equations are
y = 2x^2 - 5x - 7 - - - - - - - - - - -1
y = 2x + 2 - - - - - - - - - - - - - 2
We would equate equation 1 and equation 2. It becomes
2x^2 - 5x - 7 = 2x + 2
2x^2 - 5x - 2x - 7 - 2 = 0
2x^2 - 7x - 9 = 0
We would find two numbers such that their sum or difference is -7x and their product is - 18x^2. The two numbers are 2x and - 9x. Therefore
2x^2 + 2x - 9x - 9 = 0
2x(x + 1) - 9(x + 1) = 0
2x - 9 = 0 or x + 1 = 0
2x = 9 or x = - 1
x = 9/2 = 4.5
Substituting x = 4.5 or x = -1 into equation 2, it becomes
y = 2 × 4.5 + 2 or y = 2 × - 1 + 2
y = 11 or y = 0
Therefore, the solutions are
(4.5, 11) (- 1, 0)
40 square units is teh correct answer
