PLEASE HELPP!!
An off-shore oil platform, that is 55 metres above
sea level, is supported by floats which are anchored at
a depth of 470 metres.
On the platform there is a 35 metre-high crane. The
crane holds a cable, which has a submersible used for
platform maintenance hanging from it.
The crane has lowered the submersible 120 metres.
It continues to lower it at a speed of one metre every
three seconds.
a) Which of the following expressions correctly
expresses the distance between the submersible
and the bottom of the sea at this moment?
470 + 55+ 35 - 120
470 - [120 - (55 +35)]
(470+55) (120 - 35)
b) How long will it take the submersible to reach the
bottom?
c) How long will it take the crane to lift the
submersible to the platform level if the cable goes up at the same speed that it goes down?