A plane takes off from a hill at 750 meters above sea level and lands some time later in a town located at 50 meters below sea level. During the first part of its flight, the plane gained height at a rate of 50 meters per minute but then it started to descend at a rate of 20 meters per minute. The duration of the first part of the flight was what percent of the total flight time?

1.The duration of the descent is known.

2.The total flight time is known.

This qn is already discussed . But I still dont undesrtand the logic.

I have translated the qn to a figure(attached with this prob),as per my understanding.

Attachment:

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b = distance travelled while gaining height at a rate of 50mps

c+d= distance travelled while descending at a rate of 20mps

Qn asks for T(b)/T(c+d)

where Tb= Time to ascent ;ie time to travel distance of b.

T=Total time.time to cover b+c+d

Is there anything wrong in my understanding ? I am not sure how to proceed further .