There are (7/8) tons of rice in the cafeteria, (1/3) of this pile of rice was eaten in the first week, and (3/7) of this pile of rice was eaten in the second week. How much is left uneaten?
食堂有(7/8)吨大米，第一周吃了这堆大米的(1/3)，第二周吃了这堆大米的(3/7)．还剩下几分之几没吃？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (1/3) - (3/7)</gadget>
<output>5/21 = around 0.238095</output>

<result>5/21 = around 0.238095</result>