Complex sentence: His first Parisian works were street scenes, employing a mostly brown palette, and he sent these works back to Boston for sale, which, combined with older watercolors, provided the couple with sufficient income to sustain their stay abroad.
Split into simpler sentences: His first Parisian works were street scenes, employing a mostly brown palette. He sent these works back to Boston and their sale, combined with that of older watercolors, provided him with sufficient income to sustain his stay abroad.