My sister said: I cut 28 kilograms of grass; my brother said: I cut 9 kilograms of grass three times less than yours. Excuse me, students, how many kilograms of grass did my brother mow?
妹妹说：我割草28千克；哥哥说：我割的草比你的3倍少9千克．请问同学们，哥哥割了多少千克草？
<gadget id="calculator">28 * 3</gadget>
<output>84</output>

<gadget id="calculator">84 - 9</gadget>
<output>75</output>

<result>75</result>