Given equation of line is x – 7y + 5 = 0

⇒

Which is of the form y = mx + c, where m is the slope of the given line.

∴ slope of the given line is 1/7

Slope of the line perpendicular to the line having slope m is -1/m

Slope of the line perpendicular to the line having a slope of 1/7 is = -7

Equation of line with slope -7 and x intercept 3 is given by y = m(x – d)

⇒ y = -7 (x – 3)

⇒ y = -7x + 21

⇒ 7x + y = 21