To do this, you need to know what fraction the wedge represents, which should be given as part of the problem. Either the wedge is defined as being 1/6 or 1/8 or something like that, or the length of the arc segment will be given so that you can compare
it to the perimeter to determine this.
-x + 3 > 7
-x + 3 - 3 > 7 - 3 This step is straightforward and the same as an equality.
-x > 4 It's this next step that confuses a lot of students.
-x/-1 < 4/-1 When you divide out the negative, you flip the sign
See Nataliya's answer for the full explanation. The key point where you went wrong was on b2. The b value is -1, which means the entire value
including the negative sign is being squared, (-1)2=1. So the value under the radical should have been
1+80=81 and you accidentally ended up with...