Jimmy is trying to synchronize two clocks on the roof of two buildings. The master clock is located at (x,y,z)=(0m, 0m, 80m), the slave clock is located at ( 200m, 300m, 30m). When the master clock ticks at t=0 s, it produces a laser beam towards the slave clock. To what time should Jimmy pre-set the slave clock, so the two clocks will be in synch when they are all ticking?