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**Chain rule important formulas:**

**1.Direct Proportion:**

Two quantities are said to be directly proportional, if on the increase (or decrease) of the one, the other increases (or decreases) to the same extent.

**Example:** Cost is directly proportional to the number of articles.

(More Articles, More Cost)

**2.Indirect Proportion:**

Two quantities are said to be indirectly proportional, if on the increase of the one, the other decreases to the same extent and vice-versa.

**Example:** The time taken by a car is covering a certain distance is inversely proportional to the speed of the car. (More speed, Less is the time taken to cover a distance.)

**Note:** In solving problems by chain rule, we compare every item with the term to be found out.

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