Brian is adding the lengths of wood posts that he has left from building a pen for his chickens. A photo of chickens is shown.

The lengths are 323, 214, and 213. Brian began with 20 feet of wood.

Write and then evaluate a fraction expression to determine how much wood he used for the pen.
Enter the correct expression in the box.

2 of 2
Simplify inside the parentheses, and then subtract.

Expression: $$

He used
feet.