Write the following sentence using mathematical symbols:
The product of $6$6 and $x$x is less than or equal to $-42$−42.
Write down the inequality described by "negative four groups of $x$x is less than three", and solve for $x$x.
If $x\le-2$x≤−2, what is the largest integer value $x$x can have?
Which of the following values is not a solution of $k\le15$k≤15?