To obtain 11 equal pieces, Michael's father has to cut 10 times. If each cut changes -0.125 inches of its length, then the total change is -12.5 inches.
![-0.125\cdot10=-12.5](https://img.qammunity.org/2023/formulas/mathematics/college/5s0ul8cc1ysr5oerevpl4um6tnpwpfrvos.png)
In other words, the given situation indicates that the cuts will reduce the length of the board by 12.5 inches, that's how affects.