Grandpa has a vegetable field, which is used to grow beans and eggplants (5/8), cucumbers and persimmons (3/10), and the rest to grow potatoes, how much is used to grow potatoes?
爷爷有一块菜地，种豆角和茄子用去(5/8)，种黄瓜和柿子用去(3/10)，其余的种土豆，种土豆用了几分之几？
<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (5/8) - (3/10)</gadget>
<output>3/40 = around 0.075</output>

<result>3/40 = around 0.075</result>