Solve: 3x = 12.

## The reasoning To solve **3x = 12**, we need to isolate x (get x alone on one side). The principle here is **inverse operations** — we undo multiplication by dividing both sides by the same number. Since x is being multiplied by 3, we divide both sides by 3: 3x ÷ 3 = 12 ÷ 3 x = 4 **Quick check:** Does 3 × 4 = 12? Yes! ✓ --- ## Why the wrong options tempt you - **x = 3** tricks you if you subtract instead of divide (12 − 3 = 9... wait, that doesn't even give 3!) - **x = 6** catches you if you mistakenly do 12 ÷ 2 instead of 12 ÷ 3 - **x = 9** tempts you if you subtract 3 from 12, forgetting this is multiplication, not addition The trap is confusing which operation to reverse. Since 3 is **multiplying** x, you must **divide** to undo it. --- ## Quick takeaway **Whatever's being done to x, do the opposite to both sides** — multiply becomes divide, add becomes subtract.