#ln(4) - ln(x) =10#
#color(white)("XXXXXXXXXX")#since #log(a/b) = log(a)-log(b)#
#rArr ln(4/x) = 10#
#color(white)("XXXXXXXXXX")#taking each side of the above as an exponent of #e#
#rArr 4/x = e^10#
#color(white)("XXXXXXXXXX")#algebraic simplification
#rArr x = 4/(e^10)#