If 8a−4b=20 and 4a−8b=4, then what is the value of a−b?

Question

i got 2

Answer 1

easy way
8 a - 4 b = 20
4 a - 8 b = 4
-------------- add these
12 a - 12 b = 24
divide both sides by 12
a - b = 2