Explanation:
7x-8y = - 5 arrange to y = mx+ b form m is the slope of this line
8y = 7x+5
y = 7/8 x = 5/8 <====== m, slope = 7/8
perpendicular slope = - 1/m = - 8/7
Now use point ( -7,3) slope (-8/7) form:
y-3 = - 8/7 ( x - - 7) simplify
y = -8/7 x + 5 re-arrange , add 8/7 x to both sides of the equation
8/7 x + y = 5 multiply through by 7 to get integer values
8x + 7y = - 35