(-2/7)(-21/4)
$$\left({\frac{{\mathtt{2}}}{{\mathtt{7}}}}{\mathtt{\,\times\,}}{\frac{{\mathtt{21}}}{{\mathtt{4}}}}\right)$$
$${\frac{{\mathtt{42}}}{{\mathtt{28}}}}$$
Simplified: 1 $${\frac{{\mathtt{14}}}{{\mathtt{28}}}} = {\frac{{\mathtt{1}}}{{\mathtt{2}}}}$$