Question

@freckles

Answer 1

What is your guess?

Answer 2

you are given 2a+(b+7c)
They just want you to use properties like associative property.

Answer 3

I'd say 2a+2b+7c

Answer 4

(m+n)+z=m+(n+z) by associative property
none of the numbers change just the grouping symbols changed location

Answer 5

example 5+(3+2) =(5+3)+2

Answer 6

It doesn't matter if I put some scalars in front
(am+bn)+cz=am+(bn+cz)

Answer 7

so take a new guess

Answer 8

(2a+1b)+7c?

Answer 9

looks good