There is a plate of grapes, distributed to 20 children, for the first time, each person is divided into 3 pieces, and finally there are some leftovers, the teacher divides again, each person is divided into 4 pieces, but it is not enough, the insufficient amount is as much as the rest, How many grapes are in this dish?
有一盘葡萄，分给20个小朋友，第一次每人分3粒，最后还剩了一些，老师又重新分，每人分4粒，可又不够了，不够的和剩下的一样多，这盘葡萄是多少粒．
<gadget id="calculator">3 * 20</gadget>
<output>60</output>

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

<result>70</result>