(a)[1]
Fill in the blank to make the calculation correct: $\frac{24 + 8}{4} = \ldots$
(b)[1]
Fill in the blank to make the calculation correct: $-18 \div \ldots = 2$
(c)[1]
Fill in the blanks to make the calculation correct: $\frac{7}{8} \times \frac{\ldots}{\ldots} = \frac{21}{40}$