If 60 metres of fencing was available to make a rectangular pen with length, l, and width, w, then the formula for the area, a, of the pen is given by:
1. a = (30-l) w
2. a = (30-w) w
3. a = (30-w) l
4. a = (60-2l) w
5. a = (60-2w) l

2. (30-W)*W

Step-by-step explanation:

In order to find the answer we need the formula for the area of a rectangle, which is:

area=(length)*(width) which is:

A=L*W

Now, beacuse 60 meters of fencing were used, this means that 60 meters is the perimeter of the rectangle, so:

perimeter=(2*length)+(2*width) which is:

60=2L+2W

30=L+W which can be written as:

30-W=L

Using the area's formula we have:

A=L*W which, using the previous expression, can be written as:

A=(30-W)*W

In conclusion, the answer is 2. (30-W)*W.