dual nature of matter and radiation

Okay so, the question states that the 24 W laser has half the frequency of 6 W laser. How'd they cut hv (since one of them should be 1/hv and that should sort of not make it possible to be cut with hv I think?) to leave out the answer to be 5.0 x 10^18? And where'd the 2 in the denominator go?