Answer:
6.6
Step-by-step explanation:
The angles are the same (90°), so you just need to find the measure of the sides to see how they would be similar.
One side is 8, the other side is 10 on the big triangle.
The smaller triangle had the sides x-1 and 7 respectively.
8/10 = x-1/7
When you solve this, you get 5.6. To make it fit the equation, you would have to add one to that, which equals 6.6.
Hope this helps