Liangliang uses a 70-meter-long rope to surround a square vegetable field with a side length of 15 meters. How many meters are left?
亮亮用一根长70米的绳子，将一块边长是15米的正方形菜地围一周，还剩多少米？
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<gadget id="calculator">70 - 60</gadget>
<output>10</output>

<result>10</result>