Respuesta :

The answer to this should be a-8b+13c

a - {4b - [a - (5b - c) + 3c - (a - b - 9c)]}
=a - {4b - [a - 5b + c + 3c - a + b + 9c]}
=a - {4b - [- 4b+ 13c]}
=a - {4b + 4b -13c}
=a - 8b + 13c


Hope this helped :)
Have a great day