Question

If he is in the 12 floor and he went up 3 floor and he went down 8 floor

Answer 1

Step-by-step explanation:

Suppose their paths cross after x minutes.

Then, 11+57x=51−63x⇔120x=40⇔x=

3

1

.

Number of floors covered by David in

3

1

min. =(

3

1

×57)=19.

So, their paths cross at (11+19)th i.e. 30th floor.

Answer 2

Answer:

he is at 12th floor= 12

he went up 3 floors= +3

he went down 8 floors = -8

then,

=12+3+(-8)

=12+3-8

=15-8

=7