Help plsss 12-3x= -6x

Me ! write an equation for the interior angles of this triangle that uses the triangle sum theorem

In trapezoid bath, ah=19.7 and et=16.1. identify be.

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.