Answer:
7.
Step-by-step explanation:
21 = 3 * 7
28 = 2 * 2 * 7
42 = 2 * 3 * 7
Collecting common factors:
t is common to all 3 sets of factors so
HCF = 7.
5
b
just took it i got 100%
well you see, I don't care
