Which answer describes the calculations that could be used to solve this problem?

thomas bought a case of 6 apple juice bottles and one 3-liter bottle of orange juice. each apple juice bottle contains 2 liters of juice. how many liters of apple and orange juice did thomas buy?

a.
multiply 6 × 2. then add 3 to the product.

b.
multiply 6 × 3. then add 2 to the product.

c.
add 6 + 3. then multiply the sum by 2.

d.
add 6 + 2. then multiply the sum by 3.