Final answer:
The 3rd farmer must pay $120 as his share of the rent.
Step-by-step explanation:
To find out how much the 3rd farmer must pay as his share of the rent, we need to calculate the total number of sheep each farmer has to feed.
The 1st farmer feeds 100 sheep for 6 months, which is a total of 100 x 6 = 600 sheep-months.
The 2nd farmer feeds 120 sheep for 4 months, which is a total of 120 x 4 = 480 sheep-months.
The 3rd farmer feeds 150 sheep for 2 months, which is a total of 150 x 2 = 300 sheep-months.
Therefore, the total number of sheep-months is 600 + 480 + 300 = 1380.
To find the share of the rent for the 3rd farmer, we divide the rent by the total number of sheep-months: $552 / 1380 = $0.40 per sheep-month.
The 3rd farmer has to pay for 300 sheep-months, so the amount he must pay for his share of the rent is 300 x $0.40 = $120.