What is (x+7) (x^2-6x+1)= in simplest form

Geometry answer picture question pls . reason and statements

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

Find the number of liters in 12.8 gal of gasoline. round to the nearest hundredths