Mary’s annual income is $15,000 and John’s annual income is $18,000. By how much must Mary’s annual income increase so that it constitutes 55% of Mary and John’s combined income?

Alice’s take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did NOT save. If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?

One robot, working independently at a constant rate, can assemble a doghouse in 12 minutes. What is the maximum number of complete doghouses that can be assembled by 10 such identical robots, each working on separate doghouses at the same rate for hours?

A professional janitor can clean a certain high school in 8 hours, working at a constant rate. A student sentenced to detention can clean that same high school in 20 hours, also working at a constant rate. If the student is paid $7 total per hour and the janitor is paid $21 per hour, how much more would it cost the school to pay the janitor to do the job himself than it would to pay the student and the janitor to do the job together?

An empty swimming pool with a capacity of 5,760 gallons is filled by a pipe at the rate of 12 gallons per minute. There is an emptying pipe which, in 9 hours, can empty the pool, which is full. How many hours does it take to fill the pool, which is already half filled, if both the pipes are kept open?

An assembly machine produces 2,000 units of product per hour. Working 15 hours each day, another machine, thrice as efficient, will produce how many units of the same product in 10 days?

A water pump began filling an empty swimming pool with water and ran at a constant rate tillì the swimming pool was full. At sometime, the pool was full, and hours later, it was full. How many hours would it take the pump to fill the empty pool completely?

A printer can print 12 pages per minute. At that rate, how many seconds will the printer require to print 30 pages?

Two journalists have 8 hours in which to copy edit a total of 100 articles. If Journalist A copy edits at a steady rate of 3.5 articles per hour, how many articles per hour must Journalist B copy edit in order to complete the assignment on time?

Working alone, it takes Randy 11 hours to inventory the instrument shop. Liz can complete the same inventory in 10 hours. If they worked together, how long would it take them to complete the inventory of the instrument shop?