Mr. Rivas bought a can paint. he used 3/8 of it to paint a bookshelf. he used 1/4 of it to paint a wagon. he used some of it to paint a birdhouse and has 1/8 of the paint left. how much paint did he use for he birdhouse

The first thing you need to do is find the common denominator by multiplying the 1 and 4 in 1/4 but 2 so that both of the fractions have an 8 on the bottom. the answer should be 5/8 if you add then up correctly. there are 8/8 in a whole and we know that he has used 5/8 so far so we should subtract 5/8 from 8/8 to get 3/8. there was 1/8 left over after he painted the birdhouse so we would subtract 1/8 from 3/8 and get 2/8. so, he used 2/8 (or 1/4 if you simplify it) of a can of paint to paint the birdhouse.