Complex sentence: In the fall of 1987, having met a new boyfriend, the mother placed Child A in charge of the others and, giving him ¥50,000 (a little over US $500) for their living expenses, left her children alone in their Tokyo apartment.
Split into simpler sentences: In the fall of 1987, having met a new boyfriend, the mother placed Child A in charge of the others and. Leaving him with ¥50,000 (a little over US $500) for their living expenses alone in their Tokyo apartment.