Explanation:
direct variation is a proportional relationship between 2 sets of quantities, in which the quantities of one of the sets directly vary by the same factor with respect to the changes of the quantities of the other set. this means that an increase in one quantity results in a proportionate (the same factor for any change) increase in the other quantity.
in a formal way :
y = kx
x, y are representing quantities of the 2 sets, k is the common factor.
in our case only
y = 6x
covers this.
with every increase of x, y increases by 6 times that increase. that is a direct variation relationship.