2 cos theta - 1 = 0 trig equations

How do the graphs of y = 1/x and y=5/x+6 compare?

How to determine whether two known pairs of points are on the same line.

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is