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2(3y) - 5y = 15
6y - 5y = 15
y = 15
therefore x = 3(15) = 45
Hence, the age of Ravi is 45 years & the age of Sourav is 15 years.

Example: (Cross Multiplication)

The area of a rectangle gets reduced by 9 square units, if its length is reduced by 5
units and breadth increased by 3 units. If we increase the length by 3 units and the
breadth by 2 units, the area increases by 67 square units. Find the dimensions of the
rectangle.

Solution:

Area of any rectangle = Length x breadth

Let “x” be the length of rectangle

Let “y” be the breadth of rectangle

(x – 5) (y + 3) = xy – 9

x y + 3x - 5y – 15 = xy – 9

xy – xy + 3x – 5y – 15 + 9 = 0

3 x – 5 y – 6 = 0 -------(1)

(x + 3) (y + 2) = xy + 67

xy + 2x + 3y + 6 – xy – 67 = 0

2x + 3 y – 61 = 0 -------(2)

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