Answer:
tanks of gas
Step-by-step explanation:
Let the x be the number of tanks of gas, then
The amount of gas used by first car= ![1\frac{3}{4}x=\frac{7}{4}x](https://tex.z-dn.net/?f=1%5Cfrac%7B3%7D%7B4%7Dx%3D%5Cfrac%7B7%7D%7B4%7Dx)
The amount of gas used by second car= ![2\frac{1}{8}x=\frac{17}{8}x](https://tex.z-dn.net/?f=2%5Cfrac%7B1%7D%7B8%7Dx%3D%5Cfrac%7B17%7D%7B8%7Dx)
The amount of gas used by third car= ![1\frac{1}{2}x=\frac{3}{2}x](https://tex.z-dn.net/?f=1%5Cfrac%7B1%7D%7B2%7Dx%3D%5Cfrac%7B3%7D%7B2%7Dx)
Thus, the total change in the amount of gas for all three cars=![\frac{7}{4}x+\frac{17}{8}x+\frac{3}{2}x](https://tex.z-dn.net/?f=%5Cfrac%7B7%7D%7B4%7Dx%2B%5Cfrac%7B17%7D%7B8%7Dx%2B%5Cfrac%7B3%7D%7B2%7Dx)
![=x(\frac{7}{4}+\frac{17}{8}+\frac{3}{2})\\\\=x(\frac{14+17+12}{8})\\\\=x(\frac{43}{8})\\=5\frac{3}{8}x](https://tex.z-dn.net/?f=%3Dx%28%5Cfrac%7B7%7D%7B4%7D%2B%5Cfrac%7B17%7D%7B8%7D%2B%5Cfrac%7B3%7D%7B2%7D%29%5C%5C%5C%5C%3Dx%28%5Cfrac%7B14%2B17%2B12%7D%7B8%7D%29%5C%5C%5C%5C%3Dx%28%5Cfrac%7B43%7D%7B8%7D%29%5C%5C%3D5%5Cfrac%7B3%7D%7B8%7Dx)
Since, the amount of gas
tanks of gas is used for all three cars.
Therefore, the total amount would be negative .
hence, the answer is
tanks of gas.