It takes 1/2 of box of nails to build bird house. if you wanted to build 5 bird houses, how many boxes would you need?

For every birdhouse, you need 1/2 of a box of nails to build it. 

Using that logic we can assume that for every birdhouse you add 1/2 to get to your final answer. 

1 birdhouse:     2 birdhouses:    3 birdhouses:    4 birdhouses:    5 birdhouses:

1/2                     2/2                     3/2                      4/2                     5/2

Now, we know that the answer is that we need to have 5/2 boxes of nails to build 5 birdhouses.

5/2 can also be converted into 2 1/2.

So 2 1/2 boxes of nails would be needed is the final answer

No he does not because he can only cover 12 square feet from 15 square feet which he will still need 3 more. this is because if 3×5=15 square feet and 15-12=3 which thats the answer