A farmer buys a goat and a sheep for Rs 3500. He sold the sheep at a profit of 20 percent and the goat at a loss of 10 percent. If he sold both the animals at the same price, then the cost price (in Rs) of the cheaper animal was?

Let CP of sheep = x

then, CP of goat = 3500 - x

He sold the sheep at a profit of 20 percent and the goat at a loss of 10 percent and sold at the same price

SP of sheep = SP of goat

$$\frac{100+20}{100}\times x = \frac{100-10}{100}\times (3500-x)$$

$$\frac{120}{100}\times x = \frac{90}{100}\times (3500-x)$$

$$1.2\times x = 0.9\times (3500-x)$$

$$x = 1500$$

CP of sheep = x = 1500

then, CP of goat = 3500 - x = 3500 - 1500 = 2000

CP of cheaper = 1500/-

SO the answer is option B.