When no to use attr_reader and attr_writer in ruby

balance_boost.rb

def temporary_balance_boost
  old_balance = balance
  balance = balance * 2
  puts "Your balance is now #{balance}, you have 10 seconds to use it!"
  sleep 10
  balance = old_balance
end

def temporary_balance_boost
  old_balance = @balance
  @balance = @balance * 2
  puts "Your balance is now #{@balance}, you have 10 seconds to use it!"
  sleep 10
  @balance = old_balance
end