Answer: 6 students
What we know:
Students: 24
Students who play checkers: 
Students who also play sudoku:
of the 
24 ÷ 3 = 8, so 8 × 2 = 16 (students who play checkers)
× 2 = 
So the answer is,
6 students play both checkers and sudoku
Answer:
same I dont know your language
Step-by-step explanation:
Answer:

With the vertex 
We see that b = -10 and a = 2 and then the vertes wuld be:

And the best option is:
b. (-10,2)
Step-by-step explanation:
For this problem we have the following function:

And if we compare this expression with the general expression for a parabola given by:

With the vertex 
We see that b = -10 and a = 2 and then the vertes wuld be:

And the best option is:
b. (-10,2)