There are 5 students throwing sandbags. If the teacher gives 2 sandbags to each of them, the difference is 1. How many sandbags does the teacher have in total?
有5个同学投沙包，老师如果发给每人2个沙包就差1个，老师共有多少个沙包？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<result>9</result>