Isn't the nucleus the largest one? Why is there only one option with nucleus first and it's not in the right order?

Angle LIS is congruent to angle DIE making both of them 61°, angle LID and angle SIE are congruent as well. When you add LIS, DIE, LID, and SIE all add to 360°. So 61+61 equals 122. 360-122 is 238. You divide 238 by 2 to get 119. That will be the measure of angle SIE. A triangle is a total of 180° so add up the angles 27° + 119° to get 146°. Subtract that from 180° to get 34°.

34° is the measure of ISE

Hope this helps!