Grandma raises 139 chickens, which is 7 times the number of geese and one less. How many geese does grandma raise?
奶奶养了139只鸡，是养鹅数的7倍少1只，奶奶养鹅多少只？
<gadget id="calculator">139 + 1</gadget>
<output>140</output>

<gadget id="calculator">140 / 7</gadget>
<output>20</output>

<result>20</result>