[+15 - (+7 + 3 - 2)] - [-15 - (-6 + 7 - 1)] - (-1 + 6 - 2)
[+15 - (+7 + 3 - 2)] - [-15 - (-6 + 7 - 1)] - (-1 + 6 - 2)
45)
$[+15 - (+7 + 3 - 2)] - [-15 - (-6 + 7 - 1)] - (-1 + 6 - 2)$
$[+15 - (+8)] - [-15 - 0] - (+3)$
$[+15 -8] - [-15] -3$
$+7+15-3$
$19$