The length Q of a rectangle is decreased by 15% and its width is increased by 40%. Does the area of the rectangle decrease or increase and by what percent?
Answers.
A) Decreases by 19%
B) Decreases by 25%
C) Increases by 6%
D) Increases by 19%
E) Increases by 25%
Let the length Q of the rectangle be 100x, and width be 100y. Area = 100x * 100y = 10000xy   Now after the change Length 100  * 100= 
<gadget id="calculator">100  * 100</gadget>
<output>10_000</output>
10000xy   Now after the change Length= 85x, and width = 140 y. Area = 11900xy   % Change = (11900xy - 10000xy)/(10000xy) = 19 % Increase. Hence Increases by 19%.
<result>D</result>
The length Q of a rectangle is decreased by 15% and its width is increased by 40%. Does the area of the rectangle decrease or increase and by what percent?