What is the domain and range ​

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

Having a hard time understanding this question (see attachment).

Solve for n. round to the tenths place, if necessary. 14.2 cups of flour6 loaves of bread= 20 cups of flour n