An experienced bricklayer can construct a small wall in 4 hours. an apprentice can complete the job in 12 hours. find how long it takes if they work together.

Experienced worker takes 4hr to complete so in 1hr it would be 1/4 completed.

Apprentice worker takes 12hrs to complete, so in 1hr it would be 1/12 completed.

Team effort X hours and 1/X part of the job completed in an hour.

Set up:

1/4 + 1/12 = 1/x

Get the denominators the same to add. So multiply the left side by 3.

3/12 + 1/12 = 1/x

Combine like terms.

4/12 = 1/x

Cross multiply.

4x = 12

Dived by 4 on both sides

X = 3 hrs if they work together.

The answer is 3.