Pls, I need help on this one

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

Can someone me and do the problem plz so i can understand it more better

Which of the following is closest to 32.9 x 7.5? a: 232 b: 259 c: 220 d: 265