The window has the shape of a kite. How many square meters of glass were used to make the​ window? 20 15 20 25 are the numbers

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