Ответ:

from aiogram import Bot, Dispatcher, executor, types

from aiogram.dispatcher import FSMContext

from aiogram.contrib.fsm_storage.memory import MemoryStorage

API_TOKEN = 'TOKEN'

bot = Bot(token=API_TOKEN)

dp = Dispatcher(bot, storage=MemoryStorage())

@dp.message_handler(commands=['start', 'help'])

async def send_welcome(message: types.Message, state: FSMContext):

   await message.answer("vvedite svoi vozrast")

   await state.set_state('get_age')

@dp.message_handler(state='get_age')

async def say_verdict(message: types.Message, state: FSMContext):

   if message.text.isdigit():

       if int(message.text) >= 18:

           text = 'vi VZROSLIJ'

       else:

           text = 'vi REBENOK'

   else:

       text = 'nekorrektnij vvod'

   await message.answer(text)

   await state.finish()

if __name__ == '__main__':

   executor.start_polling(dp, skip_updates=True)