Which graph represents a function?

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

Secant be and cf intersect at point d inside a what is the measure of cde

Solve -.016x= -16. need solving this