9: John has two colored varieties of water bottles: white water bottles and black water bottles. The total number of water bottles is 20. He sold a white water bottles for $1 and a black water bottles for $2 and earned a sum of $35. Find number of black water bottles he has.

Atown is built on the banks of a small lake on the edge of a desert. after some time, the townspeople discover that water from the lake has become too polluted to use. describe one way that the lake may have been contaminated by the actions of the townspeople, and explain how the townspeople can remediate this problem.

Using complete sentences, describe the central economic problem facing all humans. why does this require people to make choices? how can this result in opportunity costs?

Is water wet? and is fire on fire?