Can someone tell me what the blue lines mean?

For each proportion find the unknown number x 1/5/8=×/15

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle

Someone answer this asap for the first five terms of a sequence are shown. 5, 11, 23, 47, 95, . . which recursive function defines the nth term in the sequence for n > 1? a. f(n) = f(n - 1) + 6 b) f(n) = f(n - 1) + 48 c) f(n) = 3 • f(n - 1) + 1 d) f(n) = 3 • f(n - 1) - 4