How many liters of a 90% acid solution must be mixed with a 30% acid solution to get 480L of a 80%solution?

a student's grade in a course is the average of 4 test grades and a final exam that is worth three times as much as[..]

Nico is saving money for his college education. He invests some money at 7% and $900 less than that amount at 4%.[..]

Starting at the same point in a forest, two hikers take different paths. The first hiker walks due north at a speed[..]

Starting st the same point in a forest, two hikers take different paths. The first hiker walks due north at a speed[..]

The track of the Duquesne Incline in Pittsburgh, Pennsylvania is about 800 feet long at an angle of elevation of 30[..]

An investor invested a total of $1,500 in two mutual funds. One fund earned a 9% profit while the other earned a 3%[..]

express commuter train #12 leaves the download station and travels at an average speed of 55 miles per hour towards[..]

Jose invests money in two simple interest accounts. he invests four times as much in an account paying 12% as he[..]

Kelly earns 25% more than cici, and together they earn $1181.25 per week. How much does Kelly earn per week?