Let the bunches of feed bought for Rs 1280 be x.
The quantity of feed bought and their cost are in direct proportion.
∴ 600/15 = 1280/x
∴ 600x = 1280 × 15 …. (Multiplying both sides by 15x)
∴ x = (1280 x 15)/600
= 32
∴ 32 bunches of feed can be bought for Rs 1280.