The height a plant grew varied directly with the number of days the plant was exposed to sunlight. what is the equation for this direct variation?
a) y = 1.09x
b) y= 1.09 + x
c) y = x - 1.09
d) y = 1.09/x

Days exposed to sunlight:       3         4        5          6
Height in inches:                     3.27    4.36   5.45     6.54

Days exposed to sunlight is the x in the equation. While height is the y in the equation. K is the constant of variation.

y = kx ; k = y/x

3.27 / 3 = 1.09
4.36 / 4 = 1.09
5.45 / 5 = 1.09
6.54 / 6 = 1.09

The equation for the direct variation is: y = 1.09x  CHOICE A.

That would be c 

x could be  any real number.