B is the correct answer
Anything within parenthesis completed first. So 6(20+1) is equal to 6(21).
A isn’t right because 21-1=20. 6(20) is not equal to 6(21)
C isn’t right because 20-1=19. 6(19) and 6(21) aren’t equal.
E and D aren’t right because 3+2=5. 5(22) and 5(21) are not equal to 6(21).
Hope this helped!!