A boat goes 100 km downstream in 10 hours, and 45 km upstream in 15 hours. The speed of the stream is?  Choices.
A) 4km/h  B) 3km/h  C) 2km/h  D) 3.5 km/h  E) E)None
100 --- 10 3.5 km/hS = 10   ? ---- 1   45 ---- 15 US =3   ? ----- 1 S = (10 - 3)/2= 
<gadget id="calculator">(10 - 3)/2</gadget>
<output>7/2 = around 3.5</output>
3.5 kmph   ANSWER:3.5 km/h
<result>D</result>
A boat goes 100 km downstream in 10 hours, and 45 km upstream in 15 hours. The speed of the stream is?