 At "t" = 450 days in Alice's frame, she calculates that since the tachyon signal has been traveling away from her at 2.4"c" for 150 days, it should now be at position x = 2.4×150 = 360 light-days in her frame, and since Bob has been traveling away from her at 0.8"c" for 450 days, he should now be at position "x" = 0.8×450 = 360 light-days in her frame as well, meaning that this is the moment the signal catches up with Bob.So, in her frame Bob receives Alice's message at "x" = 360, "t" = 450.Due to the effects of time dilation, in her frame Bob is aging more slowly than she is by a factor of formula_25, in this case 0.6, so Bob's clock only shows that 0.6×450 = 270 days have elapsed when he receives the message, meaning that in his frame he receives it at "x′" = 0, "t′" = 270.