Four car rental companies A, B, C, and D rented a parking area for their vehicles overnight. Company A parked 15 cars for 12 days, B parked 12 cars for 20 days, C parked 18 cars for 18 days, and D parked 16 cars for 15 days. If company A paid Rs. 1125 as the rent for parking, what is the combined rent paid by all four companies?

Explanation

The rent contribution by each company is proportional to the product of the number of cars and the number of days they parked. Hence, the ratio of rents is 15×12 : 12×20 : 18×18 : 16×15 = 180 : 240 : 324 : 240, which simplifies to 45 : 60 : 81 : 60. Let the common factor be k; then the rents are 45k, 60k, 81k, and 60k respectively. Given A's rent is Rs. 1125, we have 45k = 1125, so k = 25. Therefore, the total rent paid by all companies is (45 + 60 + 81 + 60)k = 246 × 25 = Rs. 6150.