True or false: {16, 17, 18, 19}=[16,19] ?

False. The interval [16,19] contains all the number beginning at 16 and ending at 19 while the set {16, 17,  18, 19} only includes the four integers.

True or false: {16, 17, 18, 19} is a subset of (16,19) ?

False. The interval (16,19) does not include 16 and 19.

True or false: {16, 17, 18, 19} is a subset of [16,19] ?

True. The interval [16,19] contains all the numbers between and including 16 and 19.