Afarmer has 100 gallons of 70% pure disinfectant. he wishes to mix it with disinfectant which is 90% pure in order to obtain 75% pure disinfectant. how much of the 90% pure disinfectant must he use?

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years

At the "no mutants allowed" country farm, every sheep has 4 legs, every chicken has two legs, and all animals have only 1 head. asked to count how many sheep and chicken are in the fields, a farm boy reports back that there are 140 feet and 50 heads. how many sheep and chicken are there? there are sheep and chicken at the farm.

Simplify. 4+3/7x-2-2/7x a. 2-5/7x b. 6-1/7x c. 2+1/7x d. 6+5/7x