I think it’s d for the standard equation
$2000*6%= what and $3000*8%=? i have given you the answer without solving it for you but the answers to these add up to 360 but i still however want you to find out what each one equals by itself.
Answer:

Variable is a symbol that represents a quantity in a mathematical expression, as used in many sciences. Variable (research), a logical set of attributes. Variable star, a type of astronomical star.

A constant, sometimes also called a "mathematical constant," is any well-defined real number which is significantly interesting in some way. A function, equation, etc., is said to "be constant" (or be a constant function) if it always assumes the same value independent of how its parameters are varied.
Answer:
Examination of the equation shows (graph):
x = 0, y = .5
Then .5 = c gives us the value of c giving
y = m x + .5 is our equation
Using y = 0, x = -1 gives
o = -1 * m + .5
m = .5
y = .5 x + .5 for the final equation
Check:
At x = 5, y = 3
3 = .5 (5) + .5 = 3