Sally answered 90% of the math testquestions and 80% of the history test questions correctly. if each test had 50 questions , how many questions in all did she answer correctly?

An advertising firm has an old computer that can prepare a whole mailing in 6 hours. with the of newer model the job is complete in 2 hours. how long would it take the newer model to do the job alone?

Nine more than four times a number is the same as one less than twice the number. find the number?

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?