Rex wanted to build fence around a rectangular lot. The lot measures 75 meters by 50 meters. How much fencing materials does he need?

The fencing materials required equals the length of the perimeter of the lot, which is shaped as a rectangle 75 metres long by 50 metres wide.

The perimeter of a rectangle is given by the following:
Perimeter=2 * (length+width)

75+75+50+50=2*(75+50)=2*125=250 m

To find out how much fencing materials Rex needs, we need to calculate the perimeter of the rectangular lot. The perimeter of a rectangle is the sum of all its sides.

In this case, the lot measures 75 meters by 50 meters. So, the length of one side is 75 meters, and the width is 50 meters.

To calculate the perimeter, we can use the formula 2 * (length + width).

Perimeter = 2 * (Length + Width)
Perimeter = 2 * (75 + 50)
Perimeter = 2 * 125
Perimeter = 250 meters

Therefore, Rex needs 250 meters of fencing materials to enclose the rectangular lot.