<span>6x=480 ft
x=80 ft.
Area = x^2 = 80^2 = 6400 sq. ft.</span>
Let's make the width 'x'.
And the length 'x+4'.
Perimeter is adding up ALL the sides.
Add: x + x + 4 + x + x + 4.
Simplify:
x + x + 4 + x + x + 4 = 4x + 8
Answer:
Option E.
Step-by-step explanation:
Let the intended length of Rebecca's swimming is = x units
and we assume the length of the pool = l units
Now it is given in the question that " She covers one fifth of her intended distance "
That means distance covered = 
" After swimming six more lengths of the pool she had covered one quarter of her intended distance"
So 


x = 20×(6l)
x = 120l
Therefore, Rebecca has to complete 120 lengths of the pool.
Option E is the answer.
The digits that can be in the ones place is 1 and 5.... I think.
4c + 36 because you have to multiple 4 x c which is 4c and then you have to multiply 4 by 9 which gives 4c + 36 (hope this helps)