I don't understand how to solve following questions(a, b, c).

Two firms, Gene's Gloves and Wally's Wallets, have factories near a lake. Both firms use a chemical for tanning leather. Some of this chemical runs into the lake. Each year Gene's Gloves dumps 15,000 gallons of the chemical and Wally's Wallets dumps 25,000 gallons of the chemical into thelake.

A new study has found that fish and other wildlife are negatively impacted by this chemical. The government has decided to cap the total combined amount of the chemical that the factories can dump into the river at 10,000 gallons/year. For an addition $1/gallon, Wally's Wallets is able to substitute each gallon of harmful chemical for one gallon of a harmless alternative. Gene's Gloves needs to use the harmful but more effective chemical to produce gloves. It costs $3/gallon to dispose of the harmful chemical safely. Assume that Gene's Gloves and Wally's Wallets maintain the same level of production under the new environmentalrestrictions.

a. Suppose the government gives each firm the right to dump 5,000 gallons/year. If the firms cannot buy or sell these dumping rights, what is the total cost to both firms for complying with theregulation?

Total cost: $

b. Suppose the firms can buy and sell these rights. How much of the chemical will Gene's Gloves dump into the lake? How much will one firm pay the other for the right to dump 1 gallon of the chemical into the lake?

The number of gallons and price will be

1. 10,000 gallons between $1 and $3
2. 10,000 gallons less than $1
3. 0 gallons more than $3
4. 5,000 gallons no trade will occur
5. 15,000 gallons between $1 and $3
6. 5,000 gallons, $2

c.If the firms can buy or sell these rights, what is the total cost to both firms for complying with theregulation?