In order to have a slope that is perpendicular, it has to be the opposite of the original. To find the original, you would have to find the value of y= in the given. Well, if you add 8 to both sides, you get 7x + 8 = 14y. To get y by itself, you have to divide everything by 14. So you get y = 1/2x + 8/14 (or 4/7).
So they slope of the graph has to be the opposite of 1/2 (as this is the value of m, in the slope-form). The opposite of 1/2 is the sign changed and the equation flipped; in other words, - 2/1. As this is the m value of the perpendicular equation, the answer would be A) y= -2x-7
