Trying to finish my homework

Question

I have a can of paint. I used 3/8 of the paint for a bookshelf. I used 1/4 to paint a wagon and I used some paint to paint a birdhouse. Now I have 1/8 of the paint left. How much did I use for the birdhouse?

Answer 1

Lets us assume I used x part of paint to paint bird house.

so

3/8 +1/4 +x +1/8=1

4/8+1/4+ x=1

6/8 +x=1

x=1- 1/8

x=2/8

x=1/4

Answer 2

1 - 3/8 - 1/4 - x = 1/8

8/8 - 3/8 - 2/8 - x = 1/8

3/8 - x = 1/8

3/8 - x - 1/8 = 0

3/8 - 1/8 = x

2/8 = x

1/4 = x