Hour hand starts at 30 degrees and moves 1/2 degree per minute
minute hand moves 6 degrees per minute
30 + 1/2x = 6x where x is the minutes after 1:00
30 = 5.5x
x = 5.4545 minutes or 1:05:27 This is when they overlap (forming a straight line)
If you want when they form an end-to-end straight line:
30 + 1/2x + 180 = 6x
210 = 5.5x
x = 38.18 ~~ 1:38:11