How to create a very simple mobile application "for 1 time"?

Question

Mobile development

My parents started a small business, they rented a mini hotel with 4 rooms. Things got better. And there were Wishlist and further promotion.
They tell me "you're a programmer". Although I am and I am engaged in algorithms and preparation in the exam. I successfully solve problems A, B, C, D on codeforce. But I don't really develop anything.
I had 2 tasks,
1) to create a simple website for a hotel
2) to create a small application
On the site, I scored for now, in the summer I want to deal with the topic in more detail. Decided to make a mobile application. But knowledge is exactly zero.
Goal: the guest takes a picture of the QR code in the hotel and installs the application, the goal is always our phone at hand, always up-to-date prices, a link to our website, he can show pictures to friends ...
The application is elementary:
- the main screen with a description + a photo and a call button
- 4 screens with a description of the rooms and the ability to open pictures of the room
All this will be edited very rarely. Prices are updated from the site.
My design is ready.
Tell me what is better to develop, preferably free, preferably simple. So far, for my purposes, I don’t have to go deep into this for the next 5 years.
I tried mit app inventor 2, but everything goes and floats on different devices. Well, primitive to disgrace. Maybe it's just that I'm not preparing it in the right way ...
Please tell me what can be used and relieve myself of the task?

Answer 1

Goal: the guest takes a picture of the QR code in the hotel and installs the application, the goal is always our phone at hand, always up-to-date prices, a link to our website, can show photos to friends...

will not install
will not show
prices will look at booking or another aggregator
Make a mobile-friendly website and promote in such aggregators

Answer 2

Android studio
https://d.android.com
I have everything. :)

Answer 3

For promotion, it is better to create a website, it is easier to find access to it than to a mob. application. It’s easy to make a one-pager, there are a lot of similar ones on youtube.

Answer 4

An application from one activity with
webView can handle your Wishlist. Essentially a shortcut to a site or browser for one site