>>80626
If you look at the filename "79756967_p3.png" and look at the url "https://www.pixiv.net/en/artworks/79756967" you should notice that the last part of the url is the ID of the picture's filename (in this case it's the part of the filename before the _p3 part, those _p# are used in galleries), thus you can get the source url by appending the ID of the picture to the generic "https://www.pixiv.net/en/artworks/" url.

Alternatively you could use https://saucenao.com/ and perform a reverse search.