Keiko always takes her water bottle with her when she hikes, and she always
drinks half a liter of water for every mile she hikes. Yesterday, she hiked a mile.
What fraction of a liter of water did she drink?
Expression:
Keiko drank_
of a liter of water.

Carley bought a jacket that was discounted 10% off the original price. the expression below represents the discounted price in dollars, based on x, the original price of the jacket.

There are a total of 75 students in the robotics club and science club. the science club has 9 more students than the robotics club. how many students are in the science club?

Atourist boat is used for sightseeing in a nearby river. the boat travels 2.4 miles downstream and in the same amount of time, it travels 1.8 miles upstream. if the boat travels at an average speed of 21 miles per hour in the still water, find the current of the river.