30 + 4x + 2 + 180 - (8 + 6x) = 180;The sum of all angles in a triangle is 180
32 + 4x - 8 - 6x = 0
2x = 24
x = 12
Bolded part, explanation: On a straight line, the sum of all angles is 180 degrees. We have the value of outside the triangle, the exterior angle, which, when is added with interior angle, gives 180 degrees. So we substract 8 + 6x from 180, that's the third angle in a triangle.
Step-by-step explanation:
All these fancy terms is confusing. We just need to substitute the original equations into the final problem statement.

We can then substitute 100 for x and solve.

(x + (3 + 5i))*(x + (3+5i))
= x^2 + x(3+5i) + x(3+5i) + (3 + 5i)^2
= x^2 + 2x(3+5i) + 9 + 6(5i) + 25i^2
= x^2 + 6x +10xi + 9 + 30i - 25
= x^2 + 6x + 10xi + 30i - 16