What is the least common denominator for 5/6 and 3/8

Can someone me with these two circle theorem questions asap?

Which expression is equivalent to -5(3x - 6/7)

The volume of the sun is approximately 1 × 10^18 cu km, while the volume of jupiter is approximately 1 × 10^15 cu km. which of the following is true? a. the volume of jupiter is approximately one thousand times the volume of the sun. b. the volume of jupiter is approximately one hundred times the volume of the sun. c. the volume of the sun is approximately one thousand times the volume of jupiter. d. the volume of the sun is approximately one hundred times the volume of jupiter.