Zach saved x dollars over the last year. Mina saved more than Zach. Which equation can be used to find how much money Mina saved last year

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

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

Which representation has a constant of variation of -2.5