Please help answering this

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

Tom had a total of $220 and he spent $35 on a basketball ticket . what percent of his money did he have left?

Ineed with number 6 , explain how to get 1978