6a-{-7b-2[2a-(2b-3a)]} = 6a-{-7b-2[2a-2b+3a]} ... Distribute the negative = 6a-{-7b-2[5a-2b]} ... Combine like terms. = 6a-{-7b-10a+4b} ... Distribute = 6a-{-10a-3b} ... Combine like terms. = 6a+10a+3b ... Distribute the negative = 16a+3b ... Combine like terms.