Answer:
$352
Explanation:
David Gave 1/5 of his money to charity
$2640 / 5 = $528
$2640 - $528 = $2112
1/3 of it to his mom
$2112 / 3 = $704
$2112 - $704 = $1408
He shared the rest of it among his 4 sisters equally
$1408 / 4 = $352
So, each of his sisters get $352