I need help to solve please

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

Check all that apply. f is a function. f is a one-to-one function. c is a function. c is a one-to-one function.

Hundred and tens tables to make 430 in five different ways