-6-30 can be factored first by taking the negative outside brackets: -(6+30), then taking 6 outside: -6(1+5). The expression can also be evaluated: contents of the brackets comes to 6, then we multiply by 6=36, then we make negative: -36. The second expression can be factored by taking 6 outside brackets: 6(c-6) but can't be evaluated because c is unknown.