a man swims downstream 30 km and upstream 12 km taking 3 hours each time, what is the speed of the man in still water?	Choose the correct choice from the following answers
A) 8	B) 7	C) 5	D) 2	E) 4
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">4 + 10</gadget>
<output>14</output>

<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<result>B</result>
a man swims downstream 30 km and upstream 12 km taking 3 hours each time, what is the speed of the man in still water?
divide(add(divide(12, 3), divide(30, 3)), const_2)
"30 - - - 3 ds = 10 ? - - - - 1 12 - - - - 3 us = 4 ? - - - - 1 m = ? m = ( 10 + 4 ) / 2 = 7 answer : b"