I don’t see the questions?!
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:
$10 coins: 21
$20 coins: 24
Step-by-step explanation:
heyy me again
So we can create 2 equations where
x = number of $10 coins
y = number of $20 coins:
x + y = 45
10x + 20y = 690
we can move equation 1 around so that we can get a value of x
x = 45 - y
now we can substitute x into the second equation
10(45 - y) + 20y = 690
450 - 10y + 20y = 690
10y = 240
y = 24
Now plug in y back into the first equation
x = 45 - y
x = 45 - 24
x = 21
Answer: 0
Step-by-step explanation:
Substituting in x=0, we get

Let say x = -(-2) where x is the distance of number on number line from 0.
x = -(-2)
x = +2.
Since +2 is positive quantity, positive quantities are written to the right of 0 on number line.
Hence it is 2 units to the right of 0.