Bananas are 4.50 yuan per kilogram, and pears are 4 yuan per kilogram. Xiaohong’s mother bought 4 kilograms of bananas and gave 30 yuan to the salesperson. The remaining money is used to buy pears. How many kilograms of pears can she buy?
香蕉每千克4.50元，梨每千克4元，小红的妈妈买了4千克香蕉，给了营业员30元，剩下的钱去买梨，能买梨多少千克？
<gadget id="calculator">4.5 * 4</gadget>
<output>18</output>

<gadget id="calculator">30 - 18</gadget>
<output>12</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<result>3</result>