The vector z=3−4i  is turned anticlockwise through an angle of 1800  and stretched 2.5 times. The complex number corresponding to the newly obtained vector is:

3−4i  i.e., (3,−4)  lie in fourth quadrant in complex plane, after turned anticlockwise through 1800  this will lie in II quadrant, therefore, the number will be −3+4i , now after stretching it 2.5 times i.e., multiplying by 2.5, the required complex number will be −152+10i .