Xiao Bingbing used one piece of RMB to buy pens. If she bought all the 10 yuan pens, she would just run out; if she bought all the 7 yuan ballpoint pens, she would have 6 yuan left. How many yuan is this in RMB?
小冰冰用一张人民币去买笔，如果全部买10元一支的钢笔，正好用完；如果全部买7元一支的圆珠笔，还剩6元．这是张多少元的人民币．
<gadget id="calculator">10 - 7</gadget>
<output>3</output>

<gadget id="calculator">6 / 3</gadget>
<output>2</output>

<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<result>20</result>