It costs a total of 100 yuan to buy a pair of glasses and a glasses case. The eyes are 80 yuan more expensive than the glasses case. How much are the glasses?
买一副眼镜和一个眼睛盒共花100元，眼睛比眼镜盒贵80元，眼镜多少元？
<gadget id="calculator">100 + 80</gadget>
<output>180</output>

<gadget id="calculator">180 / 2</gadget>
<output>90</output>

<result>90</result>