Can someone please gelp me plz im struggling

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 is greater, 7 p 5 or 7 c 5? 7p5 7c5

Solve each quadratic equation by factoring and using the zero product property. x^2 + 18x = 9x