Answer
Her balance at the beginning of the month was $\$2400$.
Work Step by Step
Let
$x$ = her balance at the beginning of the month
Her college savings grew 15 percent.
This means that her saving's balance increased by $0.15x$.
Thus,
$x+0.15x=\$2760
\\1.15x=2760
\\\frac{1.15x}{1.15}=\frac{2760}{1.15}
\\x=\$2400$
