Hello there,
To start it off, 2 x 39= 78
So a is correct that would be 2 x 30+9 = 2x39= 78
So b is correct as well. 2 x 40-1= 2 x 39= 78
c is questionable 2 x 30 +9= 60 + 9 = 69
So d is correct 18 + 60 = 78
So e is correct 100-22 = 78
So 2 x 39 is not equal to (2 x 30) +9
Hope this helped!
