C = 38+0.7*(Y - 10 - 0.1 * Y) Doesn't know Y, and we don't need to know Y!
C will be egal with 31 + 0.63 * Y, but I don't know that how does it became to "C = 31+0.63*Y"
Please show me the step by step solving this

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.