a trained covered x km at 40 kmph and another 2 x km at 20 kmph. find the average speed of the train in covering the entire 7 x km. Pick one:  A) 56  B) 18  C) 24  D) 19  E) 12
<gadget id="calculator">40 * 7</gadget>
<output>280</output>

<gadget id="calculator">40 / 40</gadget>
<output>1</output>

<gadget id="calculator">2 * 40</gadget>
<output>80</output>

<gadget id="calculator">80 / 20</gadget>
<output>4</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">280 / 5</gadget>
<output>56</output>

<result>A</result>
a trained covered x km at 40 kmph and another 2 x km at 20 kmph. find the average speed of the train in covering the entire 7 x km.
divide(multiply(40, 7), add(divide(40, 40), divide(multiply(2, 40), 20)))
"total time taken = x / 40 + 2 x / 20 hours = 5 x / 40 = x / 8 hours average speed = 7 x / ( x / 8 ) = 56 kmph answer : a"