Which equations show direct variation between a and b?
choose all answers that are correct.
a. b =0.7a
b. b= 1/8a-3
c. 5(1/a)=b
d. 1a=b

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