1. **State the problem:** We are given several equations involving variables $x$, $b$, and $a$ and need to verify or solve these equations. 2. **Given equations:** - $30 = x$ - $7 = b$ - $16 = x - b - b$ - $1 = b$ - $30 = a$ - $14 = \frac{a}{2}$ - $3 = x$ - $7 = b$ - $21 = x \cdot b - b$ 3. **Analyze the first set:** - From $30 = x$ and $7 = b$, substitute into $16 = x - b - b$: $$16 = 30 - 7 - 7 = 30 - 14 = 16$$ - This is true, so the first set is consistent. 4. **Analyze the second set:** - Given $1 = b$ and $30 = a$, check $14 = \frac{a}{2}$: $$\frac{a}{2} = \frac{30}{2} = 15$$ - But the equation states $14 = \frac{a}{2}$, which is false. - So this set is inconsistent. 5. **Analyze the third set:** - Given $3 = x$ and $7 = b$, check $21 = x \cdot b - b$: $$x \cdot b - b = 3 \times 7 - 7 = 21 - 7 = 14$$ - But the equation states $21 = x \cdot b - b$, which is false. - So this set is inconsistent. 6. **Summary:** - The first set of equations is correct. - The second and third sets have incorrect values or equations. **Final answer:** Only the first set of equations is consistent and correct.