Answer:
2/3= 14/21....red beads...4/21 blue beads...14+4= 18/21...so you need 3/21 more to finish the necklace and 3/21=1/7 in white beads
Step-by-step explanation:
2/3 - Red
4/21 - Blue
Change the red fraction so both fractions will have the same denominator
2/3 change to 14/21
Add blue and red together
14/21 + 4/21 = 18/21
Then subtract it from the total to get the white beads
21/21 - 18/21 = 3/21
Simplify it to get 1/7
Ans : 1/7