1. **State the problem:** We are given three pairs of values $(x, y)$ involving a constant $s$ and told there is a linear relationship between $x$ and $y$. We need to find which equation among the options represents this relationship.
2. **List the points:**
$$
(-2s, 24), \quad (-s, 21), \quad (s, 15)
$$
3. **Check each equation option by substituting the points:**
- Option A: $sx + 3y = 18s$
- For $x = -2s$, $y = 24$:
$$s(-2s) + 3(24) = -2s^2 + 72$$
This should equal $18s$, so:
$$-2s^2 + 72 = 18s$$
This is not generally true for all $s$.
- Option B: $3x + sy = 18s$
- For $x = -2s$, $y = 24$:
$$3(-2s) + s(24) = -6s + 24s = 18s$$
This matches perfectly.
- Check for $x = -s$, $y = 21$:
$$3(-s) + s(21) = -3s + 21s = 18s$$
Matches again.
- Check for $x = s$, $y = 15$:
$$3(s) + s(15) = 3s + 15s = 18s$$
Matches again.
- Option C: $3x + sy = 18$
- For $x = -2s$, $y = 24$:
$$3(-2s) + s(24) = -6s + 24s = 18s$$
This equals $18s$, not $18$, so this option is false.
- Option D: $sx + 3y = 18$
- For $x = -2s$, $y = 24$:
$$s(-2s) + 3(24) = -2s^2 + 72$$
This equals $18$ only if $-2s^2 + 72 = 18$, which is not true for all $s$.
4. **Conclusion:** Only option B satisfies the linear relationship for all given points.
**Final answer:**
$$3x + sy = 18s$$
Linear Relationship
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