Which calculations could be used to solve this problem?

There are 21 children at Corie's party. There are 2 times as many girls as boys at the party.

How many girls are at the party?

Choose all answers that are correct.

A.
Multiply 21 × 2. Divide the product by 3.

B.
Add 21 + 2. Divide the sum by 3.

C.
Divide 21 ÷ 3. Subtract the quotient from 21.

D.
Divide 21 ÷ 3. Multiply the quotient by 2.