This study examines the characteristics of eye movement during problem-solving based on the presentation of introductory text and illustrations in mathematics textbooks and proposes effective presentation methods. Text and illustrations were categorized into essential and supplementary content, with supplementary content further classified by its equivalence to text. Eye-tracking data revealed that students referenced both text and illustrations, transitioning their gaze from text to illustrations. Fixation duration was longest on key elements such as speech bubble and relevant objects. Regardless of presentation format, students first fixated on text before shifting to speech bubble, prioritizing problemrelevant information over sequential reading. Higher text-illustration equivalence led to greater illustration use, but students also utilized illustrations when they perceived a meaningful connection. These findings provide insights into effective text and illustration presentation for enhancing problem-solving in mathematics education.