Direct variation is one variable is proportionate to the other variable. If you take a closer look at -7x=-56y, you can see that these two are proportionate if you divide by -7 or -56.
You can also come to this conclusion by noting that there are no y-variable and x-variable without getting the origin. A line with direct variation goes through the origin.
To find the constant variation, you want the y to be free of any coefficient. To make -56y into just y, you need to divide the whole problem by -56. This becomes y=1/8 X. Remember that a direct variation equation is y=kx. K is the constant of variation (constant variation). The k in y=1/8 X is 1/8.
Hope this helped.