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1.$\displaystyle \frac{ 6- \frac{a}{6}}{\frac{a}{3}}$

2. $\displaystyle a-\frac{1}{3}=-\frac{2}{5}$

3. Solve: $\displaystyle x-10=49$

4. $\displaystyle -(-\{-[-(-64)]\})$

5. Solve (use elimination):

$\displaystyle 4x-5y=10$

$\displaystyle 3x-2y=4$

6. $\displaystyle -|-3+4|+5-7$

7. Solve (use substitution)

$\displaystyle 2x+3y=7$

$\displaystyle x-2y=7$

8. $\displaystyle \frac{18}{3} \times \frac{5}{4} \div \frac{3}{4}$

9. What fraction of $\displaystyle 4\frac{2}{3}$ is $\displaystyle \frac{4}{9}$

10. $\displaystyle 21\frac{7}{8}+3\frac{3}{4}$

11. $\displaystyle -4 \sqrt{27}+2\sqrt{12}$

12.$\displaystyle \frac{\frac{y}{b}+\frac{x}{b}}{\frac{y}{b}-\frac{x}{b}}$