29 gallons because if he uses 18 gallons to go 468 miles, he would be getting 26 mpg. 26 goes into 754 29 times, so he uses 29 gallons to go 754 miles.
First, you need to find the length of the smaller cubes side. To do this you would need to find the square root of 0.25. then you find the volume with the new found side length of the smaller cube by cubing the new side length and once you have your volume of smaller cube right it down.
Now you need to find the big cube volume by cubing its side length. Once you have found both of these volumes you subtract the smaller cube's volume from the bigger cube's volume to get the difference in size. Hope this helps
All real numbers would be the domain here
