Express $\dfrac{-64}{112}$ as a rational number with denominator 7.

To get the denominator 7, divide both the numerator and the denominator of the given rational number by the same number.

Note that 112 ÷ 7 = 16;

$\dfrac{-64}{112} = \dfrac{-64 \div 16}{112 \div 16} = \dfrac{-4}{7}$

Hence, $\mathbf{\dfrac{-64}{112} = \dfrac{-4}{7}}.$