Please can i have help with the question

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

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?

The price of a car has been reduced from $19,000 to $11,590. what is the percentage decrease of the price of the car?