Which expression could represent this phrase? three times the difference of 8 and a number

Answer 1

3(8-x) = 24-3x

unless you really meant

3(x-8) = 3x-24

which generally have different values, unless they have the same value

24-3x = 3x-24

6x = 48

x = 28/6 = 8

when x =8 the two expressions have the same value: zero