Which terms complete the product so that it is a differenceof squares? (-5x-3)(-5x+)

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

Need on this one asap im almost done with this subject

If x is 6, then 7x= a. 13 b. 42 c. 42x d. 76