How much pure alcohol should we add to 18 gallons of 35% acid solution to obtain a solution that is 55% alcohol?

Acollege is planning to construct a rectangular parking lot on land bordered on one side by a highway. the plan is to use 680 feet of fencing to fence off the other three sides. what dimensions should the lot have if the enclosed area is to be a maximum?

What is the area of a triangle with vertices at (-3 3) (-3,2) and (1,2)?

Find two numbers if their sum is 91 and the ratio is 6: 7?