The perpendicular line will have a slope of -3/7.
To find this, we first have to solve our equation for slope intercept form.
7x - 3y = 10 ----> subtract 7x
-3y = -7x + 10 ----> divide by -3
y = 7/3x - 10/3.
So we know the slope of this equation to be 7/3. Since perpendicular lines have opposite and reciprocal slopes, we know we can simply flip the fraction and make it a negative to get the new slope of -3/7.