C. 4x + y = 21
4(3) + 9 = 21
12 + 9 = 21
21 = 21
We know, 3 feet = 1 yard.
We have to convert feet to yards to calculate the ratio so that the final answer doesn't have any unit.
Therefore, 21 feet =
= 7 yards
Thus, the ratio

The fraction
is already in its simplest form.
Therefore, the given ratio as a fraction in the simplest form without any units is 
Common difference of the arithmetic sequence, is


Answer:
x = (-5/2)
Step-by-step explanation:
4 - (2x + 4) = 5
-4 from both sides
- (2x + 4) = 1
divide both sides by -1
2x + 4 = -1
-4 from both sides
2x = -5
divide both sides by 2
x = (-5/2)