Answer:
Length is 20 m and width is 4 m.
Step-by-step explanation:
Given:
Perimeter of the rectangular alley, 
Length is 5 times the width.
Let width be
.
So, as per question,
Length,
Now, perimeter of rectangle is given as:

Plug in 48 for
,
for
and
for b.

Therefore, width is 4 m.
Length is
m.
Let

be the identity matrix. Then pick whatever matrix you like for

.
Number 3 is 1:3 but I don't know what 4 is I can't see the whole problem