Answer: 140 tiles per hour.
Step-by-step explanation:
1. Let's call:
j: Jim's rate.
p: Pete's rate.
2. According to the problem, Jim completed half the floor in 8 hours and Pete completed the other half of the floor in 7 hours, therefore, you can express this as following:
[tex]8j=7p[/tex]
3. The problem says that Pete can lay 20 more tiles per hour than Jim, this means that:
[tex]p=j+20[/tex]
4. Substitute the second expression into the first expression and solve for [tex]j[/tex]:
[tex]8j=7(j+20)\\8j=7j+140\\8j-7j=140\\j=140[/tex]
5. The answer is: Jim can lay 140 tiles per hour.