You notice these two old suitcases stacked in the closet. The smaller suitcase is 25 in x 8 in x 9in, and the larger suitcase is 75 in x 20 in x 18in. The big suitcase is how many times larger than the smaller suitcase?

1. Find the volume of the smaller suitcase:

V_{\text{small}} = 25 \times 8 \times 9 = 1800 \, \text{cubic inches}

2. Find the volume of the larger suitcase:

V_{\text{large}} = 75 \times 20 \times 18 = 27000 \, \text{cubic inches}

3. Calculate how many times larger the larger suitcase is by dividing the volume of the larger suitcase by the volume of the smaller suitcase:

\text{Ratio} = \frac{27000}{1800} = 15

So, the larger suitcase is 15 times larger than the smaller suitcase.