Can someone help please :) i’ll mark brilliant

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

For what values of x is x2 + 2x = 24 true?

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers