Prime factor tree of 385

What values of c and d make the equation true?

27 is what percent of 108? 27 is % of 108

What is the explicit formula for this sequence? -7, -4, -1, 2, a.) an = 8 + (b - 1)3 b.) an = -7 + (n - 1)3 c.) an = 3 + (n -1) (-7) d.) an = -7 + (n - )