Answer:
15
Step-by-step explanation:
The constant is the term without the variable
5x+3y=15
15 is the constant
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<em>Correction to your question text: diameter, not radius.</em>
The area of a circle is given by:

The radius is half of the diameter.

Substitute and solve.

The middle is 2 :D hope this helps
For this case we have the variable
:

Now, matching each expression with its value we have:
A goes with 4
B goes with 3
C goes with 2
D goes with 1
ANswer:
A goes with 4
B goes with 3
C goes with 2
D goes with 1