500cg + 20hg =……gr

500cg = 5gram
20hg = 200gram
200gram + 5gram = 205gram.

500 cg = 500 :100: 5 gram
20 hg =20×100 :2000 gram

jadi 500 cg +20 hg =5 gram +2000 gram :2005 gram

semoga terbantu