A rectangular house has a perimeter of 140 feet. The length of the house is 50 feet. What is the width of the house in feet

Let's begin with the formula for the perimeter of a rectangle: P = 2W + 2L, where W is the width and L is the length. L = 50 feet.

We are told that P = 140 feet, and now know that this equals 2W + 2 (50 feet).

All that's left to do now is to solve for W. To simplify matters, divide this entire equation 140 ft = 2W + 100 by 2: 70 ft = W + 50 ft. Isolate W by subtracting 50 ft from both sides: 20 ft = W. This is the width we wanted.

I'm guessing 20 because perimeter is all four sides. So if the length is 50 then the other length is 50 so that's 100 already. Then 140 minus 100 equals 40.