gistfile1.txt

require 'bigdecimal'
#define rates
tax_rate = 0.07
tip_rate = 0.18

answer = {:total => 190} #initialize known round total
for subtotal in (1 .. 150).map(&:to_s)
  subtotal = BigDecimal.new(subtotal)
  total = (subtotal*(1+BigDecimal.new(tax_rate.to_s)+BigDecimal.new(tip_rate.to_s))*100.0).round/100.0
  if subtotal == subtotal.round && total == total.round && total < answer[:total]
    answer[:subtotal] = subtotal
    answer[:total] = total
  end
end
puts "subtotal: #{"%.2f" % answer[:subtotal]}"
puts "total: #{"%.2f" % answer[:total]}"