Answer:
y = -4
Step-by-step explanation:
5.1y = –0.3y – 21.6
5.1y + 0.3y = -21.6
5.4y = -21.6
y = -4
Answer:
820 
Step-by-step explanation:
Answer:
The relationship between the circumference of a circle and its diameter represent a direct variation and the constant of proportionality is equal to the constant 
Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form 
where K is the constant of proportionality
In this problem we know that
The circumference of a circle is equal to

therefore
the relationship between the circumference of a circle and its diameter is a direct variation and the constant of proportionality is equal to the constant 