So basically a line equals 180°.
If they’re giving u half of the line and say it’s 125° then you know the other side must be 55° because 180-125=55
So the box to the right of 125° will be 55°, then the angles to the top of them are the same numbers just in opposite places. So right above the original 125° will be 55°, and to the right of that it will be 125°
Then the bottom 4 angles will be the exact same as the top because they’re parallel lines so fill the bottom in the same way the top is.