Find the complex conjugate of -18 and 604i-94!!! Please help ASAP I didn't understand at all!!! :(

all real numbers are their own conjugate, since +0i = -0i

For all the rest, just switch the sign of the imaginary part
The conjugate of a-bi is a+bi
Surely your book explained this.
It may help to write in standard form first:
604i-94 = -94 + 604i