`5b +{-[3a +2(5a-2b)]-1}`

Remove the brackets one at a time starting with the innermost bracket. Distribute the 2 between the (5a-2b):

`5b+{-[3a+10a-4b]-1}`

Now remove the next bracket and take care with the negative symbols:

`5b+{-3a-10a+4b-1}`

`therefore = 5b-3a -10a +4b-1`

Now combine like terms:

`5b+4b-3a-10a-1`

`= 9b-13a-1`