Answer:
3 15/17 hour
Step-by-step explanation:
Kim: 11 hours for 1 chapter
Bethany: 6 hours for 1 chapter
Together: x hours to proof a chapter
In 1 hour:
Kim proofs 1/11 of a chapter
Bethany proofs 1/6 of a chapter
Kim and Bethany together proof 1/11 + 1/6 of a chapter
Kim and Bethany together proof 1/x of a chapter
Therefore, 1/11 + 1/6 must equal 1/x
1/11 + 1/6 = 1/x
6/66 + 11/66 = 1/x
17/66 = 1/x
x = 66/17
x = 3 15/17
Answer: 3 15/17 hour
