Answer:
21
Step-by-step explanation:

the -7 is found there twice, so it has a multiplicity of 2
the +7 is there thrice, so it has multiplicity of 3
Answer:
Two geometrical shapes which are identical in shape and size are said to be congruent. We use the symbol '≅' to denote congruence.
Step-by-step explanation:
The frequency table is attached.
Since there were 30 people out of the 60 that received cold medicine, that means that 60-30=30 people did not.
Since 26 people had a cold longer than 7 days, this means 60-26=34 had a cold that was less than or equal to 7 days.
14 people had a cold longer than 7 days and received medicine; this means that 26-14=12 people had a cold longer than 7 days and did not receive medicine.
30-14=16 people received medicine and had a cold less than or equal to 7 days.
30-12=18 people did not receive medicine and had a cold less than or equal to 7 days.