Use benchmarks to choose the customary unit you would use to measure each height of a computer with a fit length of a semi truck the amount of liquid a bathtub holds.

See below.

For the height of a computer, it would be best to use inches. Most screens would be about 10 -15 inches.

For the length of a semi-truck, we could use feet or yards. Inches would be too small and miles would be way too long.

For the amount of liquid in a bathtub, we should use gallons.

21, i'm pretty sure it's right lol