Question 954012

An aeroplane flies from A to B at a speed of 750km/h. On the returnn trip there was a strong tail wind and airplane flew at 900km/h. The return trip took 20min less than original. How many hours did the return trip take?
<pre>Let time taken on return trip (B to A), be T
Then time taken on outbound trip (A to B) = {{{T + 20/60}}}, or {{{T + 1/3}}}
We then get: {{{750(T + 1/3) = 900T}}}
750T + 250 = 900T
750T – 900T = - 250 
- 150T = - 250
T, or time taken on return trip = {{{(- 250)/(- 150)}}}, or {{{highlight_green(1&2/3)}}} hours