page from a spiral-bound notebook with lined paper

page from a spiral-bound notebook with lined paper. Handwritten notes and drawings are present. In the upper left corner, there are boxes containing "B4" and "B5". To the right of these, in the first row, are boxes with "6" and "15". In the second row, there are boxes with "5" and "14". In the third row, there are boxes with "B6", "F" (circled in red), and "13". In the fourth row, there are boxes with "B7", "3", and "12". Below the "F" and "3", there is a circled "4" crossed out with red lines, and an equals sign. To the right of the equals sign is a drawing of a skull and crossbones. A finger is visible in the bottom left of the image, pointing towards the crossed-out "4". The notebook is lying on a surface that appears to be wooden, with a diagonal grain. The image does not contain any identifiable landmarks or context that would allow for its location to be determined in Dunnae-myeon, South Korea.