How do i write k times 8 is less than 48 as an algebraic expression

For the equations below which statement is true ?

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

How do i put 3(x+7) in distributive property