Suppose that a varies directly with b and inversely with the product cd. a=15 when b=50, c=2, and d=5. Write the equation that models the relationship. A. a=9/bcd
B. a=3cd/b
C. a=b/9c •d
D. a=3b/cd
PLEASE ANSWER I HAVE TO SUBMIT SOON

i'm pretty sure it's 477,585,296, but perhaps my math is incorrect.

step-by-step explanation:

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x