Chapter 2 - Atoms, Molecules, and Ions - Exercises - Page 77: 2.74f

$Cr(CH_3COO)_3$ or $Cr(CH_3CO_2)_3$

This is an ionic compound. The cation is chromium, with a charge of 3+ (due to the Roman numeral III). The anion is acetate, which can be written as either $CH_3COO$ or $CH_3CO_2$, with a charge of 1- regardless. To have an electrically neutral atom, there must be 3 acetate ions and 1 chromium ion, hence the $Cr(CH_3COO)_3$ or $Cr(CH_3CO_2)_3$.