The format of the given line is 5x + 2y = 12. The format of a parallel line will be almost identical; only the constant will be different.
So start with the framework 5( ) + 2( ) = C and substitute -2 for x and 4 for y:
5( -2) + 2( 4 ) = C
Then C = -10 + 8, or C = -2. Thus, the desired equation is 5x + 2y = -2.