Answer: 140 tiles per hour.
Explanation:
1. Let's call:
j: Jim's rate.
p: Pete's rate.
2. You know that Jim completed half the floor in 8 hours and Pete completed the other half of the floor in 7 hours, therefore:
3. The problem says that Pete can lay 20 more tiles per hour than Jim, this means that:
4. Substitute the second expression into the first expression and solve for
:
5. The answer is: Jim can lay 140 tiles per hour.