Answer:
See Explanation
Step-by-step explanation:
Variable: daysInYear
Valid/Invalid: Valid
Reason: It begins with a letter; it is not a keyword, and it does not contain a hyphen
Variable: 4numberFiles
Valid/Invalid: Invalid
Reason: It begins with a number
Variable: Combination-month_game
Valid/Invalid: Invalid
Reason: It contains a hyphen
Variable: Suncity.school sec54
Valid/Invalid: Invalid
Reason: It contains a dot and it contains space