EMERGENCY! Please give me the correct answer!

Maria donates a fixed amount, a, to a charity each month. if she donates $300 in 12 months, what is the equation for a? a. a + 300 = 12 b. a × 300 = 12 c. a × 12 = 300 d. a + 12 = 300 e. a + 32 = 100

The graph represents the gallons of water in a water tank with respect to the number of hours since it was completely filled

How much dextrose 70% must be mixed with dextrose 5% to prepare 1,000 ml of dextrose 20%?