Solve for n: line passes through (n-3,8) (2n+7, 1) and has slope of 2 1/2

Asequence of numbers begins with 12 and progresses geometrically. each number is the previous number divided by 2. which value can be used as the common ratio in an explicit formula that represents the sequence? 1/2 2 6 12

The sum of two numbers is 86, and their difference is 20. find the two numbers

How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid in order to get a 40% solution of acid?