As given, let Jim's rate = x
Let Pete's rate =y
Jim completed half the floor in 12 hours so it's
= 12x
Pete completed the other half of the floor in 10 hours so its
=10y
As floor area is equal so,
.............(1)
Now, given is that Pete can lay 25 more tiles per hour than Jim, this gives=
...... (2)
Putting the value of y from equation (2) in equation (1) , we get

So, the equation is : 
If you want to solve it, it becomes:



Hence, Jim can lay 125 tiles and Pete can lay 25 more so 125+25=150 tiles.