imc

Question

Bricklayer Brenda takes 9 hours to build a chimney alone, and bricklayer Brandon takes 10 hours to build it alone. When they work together, they talk a lot, and their combined output decreases by 10 bricks per hour. Working together, they build the chimney in 5 hours. How many bricks are in the chimney?

Accepted Answer

Let x be the number of bricks in the chimney. The work done is the rate multiplied by the time. Using w = rt, we get x = (x9 + x10 - 10)(5). Solving for x, we get 900.