Sumas y restas de enteros (2879)

Calcula:

$7 -25 - \left[ 5-(5-7) -1 + (2-5) \right] - 9 =$

SOLUCIÓN

$7 -25 - \left[ 5-(5-7) -1 + (2-5) \right] - 9 =$

$7 -25 - \left[ 5-(-2) -1 + (-3) \right] - 9 =$

$7 -25 - \left[ 5+2 -1 -3 \right] - 9 =$

$7 -25 - 3 - 9 = \fbox{-30}$