Somebody please belp

Which addition property is being illustrated below? (type commutative or associative) (6 + 7) + 1 = 6 + (7 + 1)

Three times the sum of a number and seven is negative thirty-six. what is the number?

Talia grouped the terms and factored out the gcf of the groups of the polynomial 15x2 – 3x – 20x + 4. her work is shown below. (15x2 – 3x) + (–20x + 4) 3x(5x – 1) + 4(–5x + 1) talia noticed that she does not have a common factor. what should she do?