First, we need to find the area of the carpet. The equation for area is a=lw so plugging in the values gives us 8 * 10 = 80.
Now we need to find how much the carpet cost per square inch.
We divide price / quantity plugging in the values gives us 400 / 80 = 5
Let us check our work: 5 * 80 = 400 All check!
So for every square inch of the carpet costs $5.