Answer:
The difference is 
Step-by-step explanation:
We must find the common denominator of the fractions.
The common denominator of
and
is
; therefore we have


now it is easy to subtract
using the number line: we have to move
units to the left in order to get to
.
Thus our answer is

Answer:
12.6
Step-by-step explanation:
sorry only first one
Answer:
255 m
Step-by-step explanation:
From the given question, the surface of the water body is the reference point. And this point is assumed to be 0, so that any distance above it is positive, and any distance below is negative. This is synonymous to the number line system.
Thus,
For the aircraft, its height = +200 m
For the submarine, its depth = -55 m
So that the difference between the submarine and aircraft can be determined as;
200 - (-55)
= 200 + 55
= 255 m
The distance between the submarine and aircraft is 255 m.