Question

2. If the price of rice is reduced by 10%, 2kg more
rice can be bought for $180. What is the difference
between the original price and the reduced price?

Answer 1

Answer:

With $180 you can buy:-

- either $180/$10 = 18 kgs at the original price

- or $180/$9 = 20 kgs at the reduced price

The difference is 20 kgs - 18 kgs = 2 kgs

Step-by-step explanation:

If X is the original price per kg in dollars:-

- the reduced price is 90% of X = X * 9/10

- with $180 you can buy:-

- either 180/X kgs at the original price

- or 180/(X * 9/10) = 200/X kgs at the reduced price

The difference between the two quantities of rice that you can buy (at the original price and at the reduced price) is 2 kgs, so:-

180/X kgs + 2 kgs = 200/X kgs

Multiply both sides of the equation by X and you have:-

180 kgs + 2X kgs = 200 kgs

2X kgs = 200 kgs - 180 kgs

2X kgs = 20 kgs

X = $10 = original price per kg

$10 * 9/10 = $9 = reduced price per kg