"(In) the picture is an illustration used in the calendar as a supplement.
I worked on July and August."
She drew an illustration to be used in a calendar supplemented to a certain issue of the magazine. Apparently it was a bi-monthly calendar, and this illustration of hers was used on the fourth page (July and August).
Both sentences make enough sense, at least to a native speaker.
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Verified answer
Seems like it's from a blog of a manga artist:
http://blog.sakurakoujien.lolipop.jp/?eid=996285
"(In) the picture is an illustration used in the calendar as a supplement.
I worked on July and August."
She drew an illustration to be used in a calendar supplemented to a certain issue of the magazine. Apparently it was a bi-monthly calendar, and this illustration of hers was used on the fourth page (July and August).
Both sentences make enough sense, at least to a native speaker.
Shashin wa furoku no karendaa you no irasuto. Shichi-Hachi gatsu tantou deshita?
The photo calendar for illustration annex.
Was responsible for July-August.
It's not really two complete sentences. The first one lacks a verb.