It takes 365 days for the earth to go around the sun, which is 13 days longer than four times the time for Mercury to go around the sun. How many days does Mercury take to orbit the sun? (solution by equation)
地球绕太阳一周要用365天，比水星绕太阳一周所用的时间的4倍多13天．水星绕太阳一周要用多少天？(用方程解)
<gadget id="calculator">365 - 13</gadget>
<output>352</output>

<gadget id="calculator">352 / 4</gadget>
<output>88</output>

<result>88</result>