Hello from MrBillDoesMath!
Answer:
x <= 3
Discussion:
The question is equivalent to
7x <= 21
Note how "not greater than" is equivalent to "less than or equal to"
Divide both sides of the above inequality by 7:
(7/7)x <= 21/7 =< as 7/7 = 1
x <= 3
Thank you,
MrB