I need help with this

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

Plzzz i beg u so much asaaaap ! what is the slope of this line? enter your answer in the box.

Can someone me out here and the tell me the greatest common factor