What is the cost of constructing a fence 6 and a half feet (6'6") high around a lot measuring 90 ft by 175 ft; if the cost of erecting the fence is $1.25 per linear ft and the cost of materials is $.825 per square ft?

Based on the given values, I can only assume that the fence forms a rectangular shape. With this, the perimeter of the lot is:

Perimeter of lot = 2 * 90 + 2 * 175

Perimeter of lot = 180 + 350

Perimeter of lot = 530 feet 

Since the cost per linear feet (perimeter) is $1.25, therefore the cost of erecting the fence is:
Cost of erecting fence = $1.25 * 530

Cost of erecting fence = $662.50 

The area of the fence would be equal to the perimeter multiplied by the height:
Area of fence = 530 feet long * 6.5 feet high

Area of fence = 3445 square feet 

Then the cost of materials will be:
Cost of materials = 3445 * $.825

Cost of materials = $2,842.13 

Therefore the total cost would be: 
Total cost = $662.50 + $2,842.13 

Total cost = $3504.63