# The fir method returns a number.
# === Formula
# _fir_ debt
# -------------------- = some result
# a/e
# === Parameters
# The parameters are:
# * d = debt
# * e = equity
# === Example
# ratios = Ratios.new( 2, 9)
# ratios.fir # => some text
# ratios.fir 1, 5# => some text
def fir( debt=@debt, equity=@equity )
ratio = debt/(debt+equity).to_f
printf( "The long-term debt ratio is %.2f.\n", ratio )
ratio
end