Question

2×78 in expanded form

Answer 1

78+78 (156). Expanded form basically repeats the amount of numbers . It could be 2 78 times, but that is just ridiculous and could be expressed as 78+78 as supported by commutative property.

Answer 2

(2×70) + (2×8)
I'm not sure if you mean it this way the other way is like 2 78 times or 78 2 times