Please help, I can't get it right T-T

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

Long division the problem is 40 ➗ 348 = ?

Which expression gives you the distance between the points (5,1)and(9,-6)