Question

Length of a rectangle is increased by 40% and its breadth decreases by 20%

Answer 1

suppose
length is 100
breadth is 50
then
$\\ area \: of \: rectangle \\ = l \times b \\ = 100 \times 50 \\ = 5000 \\ now \: new \: length \: = 140 \\ new \: breadth = \frac{50 \times 80}{100} = 40 \\ new \: area = 140 \times 40 = 5600 \\ area \: increased = \frac{(5600 - 5000) \times 100}{5000} \\ = \frac{600 \times 100}{5000} \\ = 12\%$