Answer:
4d
Step-by-step explanation:
d=1d
1d+2d+1d=4d
(ignore the ds when adding the variable together (don't do this with variables that aren't the same thing (don't do 3x + 5y = 8xy)))
d + 2d + d = 4d
** d is the same as 1d. ....so if it makes it any easier, write it like :
1d + 2d + 1d = 4d
