Question 735204
we have the following

log base 10 (n^2 - 90n) = 3

first take log base 10 of both sides of equal sign and we have,

n^2 - 90n = log base 10 (3) = .48

use quadratic formula and we get (note that b is --90 or 90)

n=(90+square root (90^2-4*1*-.48)) / 2 = 90
=(90-square root (90^2-4*1*-.48)) / 2 = 0