Xiaohong planted 5 rows of radishes, 9 in each row, and gave 15 to grandma. How many radishes are left?
小红种了5行萝卜，每行9个，送给奶奶15个，还剩多少个萝卜？
<gadget id="calculator">9 * 5</gadget>
<output>45</output>

<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<result>30</result>