Given the size and mass of each of the solid cubes X and Y, how many

times is the density of cube X greater than the density of cube Y?

Since

density = mass/volume (which is just another word for size)

density of cube X = (cube X's mass) / (cube X's volume)

lets name " (cube X's mass) / (cube X's volume) " as "x"

density of cube Y = (cube Y's mass) / (cube Y's volume)

lets name " (cube Y's mass) / (cube Y's volume) " as "y"

then to calculate how many times is the density of cube X to density of cube Y, then it will be x/y

if calculating how many times greater, then it is (x-y) / y

though the phrase "how many times greater" can also mean "how many times".