Lmk if it’s wrong !!!!!!!!!!!!!!!
So 12 more than half the regular price.
let's let

be the original price.

right?
Now you just have to solve from there.
Formula of direct variation is: y = kx
k is the constant of variation
y is the total value that is directly varies with the changes in x.
in this case. x is represented by a. y is represented by b.
A.) b = 0.7a ⇒DIRECT VARIATION with 0.7 as the constant of variation
B.) b = 1/8 a⁻³ ⇒ Not a direct variation. Because a has a negative exponent
C.) 5(1/a) = b ⇒ Not a direct variation
D.) 1a = b ⇒ DIRECT VARIATION with 1 as the constant of variation