z=a+bi where a and b are real numbers and i is one unit in the imaginary plane.
2(a+bi)+3(a−bi)=−25−2i
2a+2bi+3a−3bi=−25−2i
5a−bi=−25−2i
The real number parts of the equation are equal and the imaginary parts of the equation are equal:
5a=−25
−bi=−2i
Now, we can obtain that a=−5 and b=2.
Thus, z=−5+2i.