7 is prime, and 15 is not a multiple of it, so the answer is 1. ■
105
LCD(15, 7, 8) = 840.
The LCD of x, 5, 7, 15 is 105x.
60
For 7/12 and 7/15 the LCD is 60.
15
LCD(9, 15) = 45
LCD(15, 26) = 390
60
LCD(7, 4) = 28
lcd(7, 97) = 679.
LCD of 7 and 37 is 259.
LCD(7, 77) = 77