Challenge 1: = vs. is on the Same Expression — Possible Solution
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SWI-Prolog session:

    ?- X = 3 * 4.
    X = 3*4.

    ?- X is 3 * 4.
    X = 12.

Explanation:
`X = 3 * 4` performs unification -- X is unified with the actual,
unevaluated compound term 3*4 (functor *, arguments 3 and 4), which
is why swipl echoes it back as "3*4", not a computed number. `X is
3 * 4` is completely different: is FORCES the right-hand side to be
evaluated as a genuine arithmetic expression first, producing the
number 12, and only THEN unifies X with that resulting number. The
same textual expression, 3 * 4, means "an unevaluated term" under =
and "an arithmetic computation to perform" under is -- exactly the
distinction the chapter's own X = 2+3 vs. X is 2+3 example
demonstrates.

WHY THIS WORKS AS AN ANSWER
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This reproduces the chapter's own core = vs. is demonstration with a
different arithmetic expression, confirming the identical distinction
holds and explaining why in terms of evaluation vs. unification.