A1400 sq ft house is advertised for sale at a price of $125,000. what is the cost per square foot?

The answer is $89.28.

Let's use the proportion for this:
If 1400 ft² costs $125,000, 1 ft² will cost x:
1400 ft² : $125,000 = 1 ft² : x

Now, crossing the products:
x · 1400 ft² = $125,000 · 1 ft²
x · 1400 = $125,000
x = $125,000 ÷ 1400
x = $89.28

Therefore, 1 square foot costs $89.28.

If you would like to know the cost per square foot, you can calculate this using the following steps:

1400 sq ft house ... $125,000
1 sq ft ... $x = ?

1400 * x = 125,000 * 1
1400 * x = 125,000
x = 125,000 / 1400
x = $89.29

The correct result would be $89.29.