currency.rb

class Currency
  def convert(amount, currency, target_currency)
    price = amount

    if currency == "USD" && target_currency == "BRL"
      price = (amount * 3.16)
    elsif currency == "BRL" && target_currency == "USD"
      price = (amount / price)
    elsif currency == "USD" && target_currency == "EUR"
      price = (amount * 0.80)
    elsif currency == "EUR" && target_currency == "USD"
      price = (amount / price)
    end

    price
  end
end