If the cost of a certain house in 1983 was 300 percent of its cost in 1970, by what percent did the cost increase ?

If machine X can produce 1000 bolts in 4 hours and Machine Y can produce 1000 bolts in 5 hours, how many hours can Machine X and Y, working together at these constant rates, produce 1000 bolts?

If 6 pounds of nuts that cost 1.20 $ per pound are mixed with 2 pounds of nuts that cost 1.60$ per pound what is the cost per pound of the misture?

How many liters of a solution that is 15 % salt must be added to 5 liters of a solution that is 8 percent salt so that the resulting solution is 10 % salt?